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Ingo Molnar 630e1e0bcd Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Conflicts:
	arch/x86/kernel/ptrace.c

Pull the latest RCU tree from Paul E. McKenney:

"       The major features of this series are:

  1.	A first version of no-callbacks CPUs.  This version prohibits
  	offlining CPU 0, but only when enabled via CONFIG_RCU_NOCB_CPU=y.
  	Relaxing this constraint is in progress, but not yet ready
  	for prime time.  These commits were posted to LKML at
  	https://lkml.org/lkml/2012/10/30/724, and are at branch rcu/nocb.

  2.	Changes to SRCU that allows statically initialized srcu_struct
  	structures.  These commits were posted to LKML at
  	https://lkml.org/lkml/2012/10/30/296, and are at branch rcu/srcu.

  3.	Restructuring of RCU's debugfs output.  These commits were posted
  	to LKML at https://lkml.org/lkml/2012/10/30/341, and are at
  	branch rcu/tracing.

  4.	Additional CPU-hotplug/RCU improvements, posted to LKML at
  	https://lkml.org/lkml/2012/10/30/327, and are at branch rcu/hotplug.
  	Note that the commit eliminating __stop_machine() was judged to
  	be too-high of risk, so is deferred to 3.9.

  5.	Changes to RCU's idle interface, most notably a new module
  	parameter that redirects normal grace-period operations to
  	their expedited equivalents.  These were posted to LKML at
  	https://lkml.org/lkml/2012/10/30/739, and are at branch rcu/idle.

  6.	Additional diagnostics for RCU's CPU stall warning facility,
  	posted to LKML at https://lkml.org/lkml/2012/10/30/315, and
  	are at branch rcu/stall.  The most notable change reduces the
  	default RCU CPU stall-warning time from 60 seconds to 21 seconds,
  	so that it once again happens sooner than the softlockup timeout.

  7.	Documentation updates, which were posted to LKML at
  	https://lkml.org/lkml/2012/10/30/280, and are at branch rcu/doc.
  	A couple of late-breaking changes were posted at
  	https://lkml.org/lkml/2012/11/16/634 and
  	https://lkml.org/lkml/2012/11/16/547.

  8.	Miscellaneous fixes, which were posted to LKML at
  	https://lkml.org/lkml/2012/10/30/309, along with a late-breaking
  	change posted at Fri, 16 Nov 2012 11:26:25 -0800 with message-ID
  	<20121116192625.GA447@linux.vnet.ibm.com>, but which lkml.org
  	seems to have missed.  These are at branch rcu/fixes.

  9.	Finally, a fix for an lockdep-RCU splat was posted to LKML
  	at https://lkml.org/lkml/2012/11/7/486.  This is at rcu/next. "

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-12-03 06:27:05 +01:00
James Hogan 84ecfd15f5 modsign: add symbol prefix to certificate list
Add the arch symbol prefix (if applicable) to the asm definition of
modsign_certificate_list and modsign_certificate_list_end. This uses the
recently defined SYMBOL_PREFIX which is derived from
CONFIG_SYMBOL_PREFIX.

This fixes the build of module signing on the blackfin and metag
architectures.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Howells <dhowells@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-12-03 13:06:25 +10:30
Joonsoo Kim 3657600040 workqueue: add WARN_ON_ONCE() on CPU number to wq_worker_waking_up()
Recently, workqueue code has gone through some changes and we found
some bugs related to concurrency management operations happening on
the wrong CPU.  When a worker is concurrency managed
(!WORKER_NOT_RUNNIG), it should be bound to its associated cpu and
woken up to that cpu.  Add WARN_ON_ONCE() to verify this.

Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-12-01 16:45:45 -08:00
Joonsoo Kim 999767beb1 workqueue: trivial fix for return statement in work_busy()
Return type of work_busy() is unsigned int.
There is return statement returning boolean value, 'false' in work_busy().
It is not problem, because 'false' may be treated '0'.
However, fixing it would make code robust.

Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-12-01 16:45:40 -08:00
Tejun Heo 8852aac25e workqueue: mod_delayed_work_on() shouldn't queue timer on 0 delay
8376fe22c7 ("workqueue: implement mod_delayed_work[_on]()")
implemented mod_delayed_work[_on]() using the improved
try_to_grab_pending().  The function is later used, among others, to
replace [__]candel_delayed_work() + queue_delayed_work() combinations.

Unfortunately, a delayed_work item w/ zero @delay is handled slightly
differently by mod_delayed_work_on() compared to
queue_delayed_work_on().  The latter skips timer altogether and
directly queues it using queue_work_on() while the former schedules
timer which will expire on the closest tick.  This means, when @delay
is zero, that [__]cancel_delayed_work() + queue_delayed_work_on()
makes the target item immediately executable while
mod_delayed_work_on() may induce delay of upto a full tick.

This somewhat subtle difference breaks some of the converted users.
e.g. block queue plugging uses delayed_work for deferred processing
and uses mod_delayed_work_on() when the queue needs to be immediately
unplugged.  The above problem manifested as noticeably higher number
of context switches under certain circumstances.

The difference in behavior was caused by missing special case handling
for 0 delay in mod_delayed_work_on() compared to
queue_delayed_work_on().  Joonsoo Kim posted a patch to add it -
("workqueue: optimize mod_delayed_work_on() when @delay == 0")[1].
The patch was queued for 3.8 but it was described as optimization and
I missed that it was a correctness issue.

As both queue_delayed_work_on() and mod_delayed_work_on() use
__queue_delayed_work() for queueing, it seems that the better approach
is to move the 0 delay special handling to the function instead of
duplicating it in mod_delayed_work_on().

Fix the problem by moving 0 delay special case handling from
queue_delayed_work_on() to __queue_delayed_work().  This replaces
Joonsoo's patch.

[1] http://thread.gmane.org/gmane.linux.kernel/1379011/focus=1379012

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Anders Kaseorg <andersk@MIT.EDU>
Reported-and-tested-by: Zlatko Calusic <zlatko.calusic@iskon.hr>
LKML-Reference: <alpine.DEB.2.00.1211280953350.26602@dr-wily.mit.edu>
LKML-Reference: <50A78AA9.5040904@iskon.hr>
Cc: Joonsoo Kim <js1304@gmail.com>
2012-12-01 16:43:18 -08:00
Mike Galbraith 412d32e6c9 workqueue: exit rescuer_thread() as TASK_RUNNING
A rescue thread exiting TASK_INTERRUPTIBLE can lead to a task scheduling
off, never to be seen again.  In the case where this occurred, an exiting
thread hit reiserfs homebrew conditional resched while holding a mutex,
bringing the box to its knees.

PID: 18105  TASK: ffff8807fd412180  CPU: 5   COMMAND: "kdmflush"
 #0 [ffff8808157e7670] schedule at ffffffff8143f489
 #1 [ffff8808157e77b8] reiserfs_get_block at ffffffffa038ab2d [reiserfs]
 #2 [ffff8808157e79a8] __block_write_begin at ffffffff8117fb14
 #3 [ffff8808157e7a98] reiserfs_write_begin at ffffffffa0388695 [reiserfs]
 #4 [ffff8808157e7ad8] generic_perform_write at ffffffff810ee9e2
 #5 [ffff8808157e7b58] generic_file_buffered_write at ffffffff810eeb41
 #6 [ffff8808157e7ba8] __generic_file_aio_write at ffffffff810f1a3a
 #7 [ffff8808157e7c58] generic_file_aio_write at ffffffff810f1c88
 #8 [ffff8808157e7cc8] do_sync_write at ffffffff8114f850
 #9 [ffff8808157e7dd8] do_acct_process at ffffffff810a268f
    [exception RIP: kernel_thread_helper]
    RIP: ffffffff8144a5c0  RSP: ffff8808157e7f58  RFLAGS: 00000202
    RAX: 0000000000000000  RBX: 0000000000000000  RCX: 0000000000000000
    RDX: 0000000000000000  RSI: ffffffff8107af60  RDI: ffff8803ee491d18
    RBP: 0000000000000000   R8: 0000000000000000   R9: 0000000000000000
    R10: 0000000000000000  R11: 0000000000000000  R12: 0000000000000000
    R13: 0000000000000000  R14: 0000000000000000  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018

Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
2012-12-01 15:56:42 -08:00
Linus Torvalds 455e987c0c Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
 "This is mostly about unbreaking architectures that took the UAPI
  changes in the v3.7 cycle, plus misc fixes."

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf kvm: Fix building perf kvm on non x86 arches
  perf kvm: Rename perf_kvm to perf_kvm_stat
  perf: Make perf build for x86 with UAPI disintegration applied
  perf powerpc: Use uapi/unistd.h to fix build error
  tools: Pass the target in descend
  tools: Honour the O= flag when tool build called from a higher Makefile
  tools: Define a Makefile function to do subdir processing
  x86: Export asm/{svm.h,vmx.h,perf_regs.h}
  perf tools: Fix strbuf_addf() when the buffer needs to grow
  perf header: Fix numa topology printing
  perf, powerpc: Fix hw breakpoints returning -ENOSPC
2012-12-01 13:07:48 -08:00
Gao feng 879a3d9dbb cgroup: use cgroup_addrm_files() in cgroup_clear_directory()
cgroup_clear_directory() incorrectly invokes cgroup_rm_file() on each
cftset of the target subsystems, which only removes the first file of
each set.  This leaves dangling files after subsystems are removed
from a cgroup root via remount.

Use cgroup_addrm_files() to remove all files of target subsystems.

tj: Move cgroup_addrm_files() prototype decl upwards next to other
    global declarations.  Commit message updated.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-30 11:44:12 -08:00
Frederic Weisbecker 91d1aa43d3 context_tracking: New context tracking susbsystem
Create a new subsystem that probes on kernel boundaries
to keep track of the transitions between level contexts
with two basic initial contexts: user or kernel.

This is an abstraction of some RCU code that use such tracking
to implement its userspace extended quiescent state.

We need to pull this up from RCU into this new level of indirection
because this tracking is also going to be used to implement an "on
demand" generic virtual cputime accounting. A necessary step to
shutdown the tick while still accounting the cputime.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Gilad Ben-Yossef <gilad@benyossef.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
[ paulmck: fix whitespace error and email address. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-30 11:40:07 -08:00
Steven Rostedt 9366c1ba13 ring-buffer: Fix race between integrity check and readers
The function rb_check_pages() was added to make sure the ring buffer's
pages were sane. This check is done when the ring buffer size is modified
as well as when the iterator is released (closing the "trace" file),
as that was considered a non fast path and a good place to do a sanity
check.

The problem is that the check does not have any locks around it.
If one process were to read the trace file, and another were to read
the raw binary file, the check could happen while the reader is reading
the file.

The issues with this is that the check requires to clear the HEAD page
before doing the full check and it restores it afterward. But readers
require the HEAD page to exist before it can read the buffer, otherwise
it gives a nasty warning and disables the buffer.

By adding the reader lock around the check, this keeps the race from
happening.

Cc: stable@vger.kernel.org # 3.6
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-30 11:09:57 -05:00
Steven Rostedt 54f7be5b83 ring-buffer: Fix NULL pointer if rb_set_head_page() fails
The function rb_set_head_page() searches the list of ring buffer
pages for a the page that has the HEAD page flag set. If it does
not find it, it will do a WARN_ON(), disable the ring buffer and
return NULL, as this should never happen.

But if this bug happens to happen, not all callers of this function
can handle a NULL pointer being returned from it. That needs to be
fixed.

Cc: stable@vger.kernel.org # 3.0+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-30 11:09:28 -05:00
Glauber Costa 1f869e8711 cgroup: warn about broken hierarchies only after css_online
If everything goes right, it shouldn't really matter if we are spitting
this warning after css_alloc or css_online. If we fail between then,
there are some ill cases where we would previously see the message and
now we won't (like if the files fail to be created).

I believe it really shouldn't matter: this message is intended in spirit
to be shown when creation succeeds, but with insane settings.

Signed-off-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-30 07:11:07 -08:00
Linus Walleij d202b7b970 irqdomain: stop screaming about preallocated irqdescs
In the simple irqdomain: don't shout warnings to the user,
there is no point. An informational print is sufficient.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2012-11-30 09:02:35 +00:00
Rafael J. Wysocki 170bb4c800 Merge branch 'pm-sleep'
* pm-sleep:
  PM / Freezer: Fixup compile error of try_to_freeze_nowarn()
  driver core / PM: move the calling to device_pm_remove behind the calling to bus_remove_device
  PM / Hibernate: use rb_entry
  PM / sysfs: replace strict_str* with kstrto*
2012-11-29 21:46:48 +01:00
Rafael J. Wysocki 9ee71f513c Merge branch 'pm-cpuidle'
* pm-cpuidle:
  cpuidle: Measure idle state durations with monotonic clock
  cpuidle: fix a suspicious RCU usage in menu governor
  cpuidle: support multiple drivers
  cpuidle: prepare the cpuidle core to handle multiple drivers
  cpuidle: move driver checking within the lock section
  cpuidle: move driver's refcount to cpuidle
  cpuidle: fixup device.h header in cpuidle.h
  cpuidle / sysfs: move structure declaration into the sysfs.c file
  cpuidle: Get typical recent sleep interval
  cpuidle: Set residency to 0 if target Cstate not enter
  cpuidle: Quickly notice prediction failure in general case
  cpuidle: Quickly notice prediction failure for repeat mode
  cpuidle / sysfs: move kobj initialization in the syfs file
  cpuidle / sysfs: change function parameter
2012-11-29 21:46:14 +01:00
Rafael J. Wysocki d4c091f13d Merge branch 'acpi-general'
* acpi-general: (38 commits)
  ACPI / thermal: _TMP and _CRT/_HOT/_PSV/_ACx dependency fix
  ACPI: drop unnecessary local variable from acpi_system_write_wakeup_device()
  ACPI: Fix logging when no pci_irq is allocated
  ACPI: Update Dock hotplug error messages
  ACPI: Update Container hotplug error messages
  ACPI: Update Memory hotplug error messages
  ACPI: Update CPU hotplug error messages
  ACPI: Add acpi_handle_<level>() interfaces
  ACPI: remove use of __devexit
  ACPI / PM: Add Sony Vaio VPCEB1S1E to nonvs blacklist.
  ACPI / battery: Correct battery capacity values on Thinkpads
  Revert "ACPI / x86: Add quirk for "CheckPoint P-20-00" to not use bridge _CRS_ info"
  ACPI: create _SUN sysfs file
  ACPI / memhotplug: bind the memory device when the driver is being loaded
  ACPI / memhotplug: don't allow to eject the memory device if it is being used
  ACPI / memhotplug: free memory device if acpi_memory_enable_device() failed
  ACPI / memhotplug: fix memory leak when memory device is unbound from acpi_memhotplug
  ACPI / memhotplug: deal with eject request in hotplug queue
  ACPI / memory-hotplug: add memory offline code to acpi_memory_device_remove()
  ACPI / memory-hotplug: call acpi_bus_trim() to remove memory device
  ...

Conflicts:
	include/linux/acpi.h (two additions at the end of the same file)
2012-11-29 21:43:06 +01:00
Rafael J. Wysocki c8b6817103 Merge branch 'pm-qos'
* pm-qos:
  PM / QoS: Handle device PM QoS flags while removing constraints
  PM / QoS: Resume device before exposing/hiding PM QoS flags
  PM / QoS: Document request manipulation requirement for flags
  PM / QoS: Fix a free error in the dev_pm_qos_constraints_destroy()
  PM / QoS: Fix the return value of dev_pm_qos_update_request()
  PM / ACPI: Take device PM QoS flags into account
  PM / Domains: Check device PM QoS flags in pm_genpd_poweroff()
  PM / QoS: Make it possible to expose PM QoS device flags to user space
  PM / QoS: Introduce PM QoS device flags support
  PM / QoS: Prepare struct dev_pm_qos_request for more request types
  PM / QoS: Introduce request and constraint data types for PM QoS flags
  PM / QoS: Prepare device structure for adding more constraint types
2012-11-29 21:40:32 +01:00
David S. Miller 8a2cf062b2 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-11-29 12:51:17 -05:00
Al Viro 541880d9a2 do_coredump(): get rid of pt_regs argument
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 00:01:25 -05:00
Al Viro 4aaefee589 print_fatal_signal(): get rid of pt_regs argument
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 00:01:25 -05:00
Al Viro 94eb22d505 ptrace_signal(): get rid of unused arguments
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 00:01:24 -05:00
Al Viro b7f9591c44 get rid of ptrace_signal_deliver() arguments
the first one is equal to signal_pt_regs(), the second is never used
(and always NULL, while we are at it).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 00:01:24 -05:00
Al Viro e80d6661c3 flagday: kill pt_regs argument of do_fork()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 00:01:08 -05:00
Al Viro 18c26c27ae death to idle_regs()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-28 23:43:42 -05:00
Al Viro 62e791c1b8 don't pass regs to copy_process()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-28 23:43:42 -05:00
Al Viro afa86fc426 flagday: don't pass regs to copy_thread()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-28 23:43:42 -05:00
Al Viro c62d773a37 audit: no nested contexts anymore...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-28 21:53:36 -05:00
Al Viro d2125043ae generic sys_fork / sys_vfork / sys_clone
... and get rid of idiotic struct pt_regs * in asm-generic/syscalls.h
prototypes of the same, while we are at it.  Eventually we want those
in linux/syscalls.h, of course, but that'll have to wait a bit.

Note that there are *three* variants of sys_clone() order of arguments.
Braindamage galore...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-28 21:49:04 -05:00
Al Viro c4144670fd kill daemonize()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-28 21:49:02 -05:00
Greg Thelen 9718ceb343 cgroup: list_del_init() on removed events
Use list_del_init() rather than list_del() to remove events from
cgrp->event_list.  No functional change.  This is just defensive
coding.

Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-28 13:52:14 -08:00
Greg Thelen 205a872bd6 cgroup: fix lockdep warning for event_control
The cgroup_event_wake() function is called with the wait queue head
locked and it takes cgrp->event_list_lock. However, in cgroup_rmdir()
remove_wait_queue() was being called after taking
cgrp->event_list_lock.  Correct the lock ordering by using a temporary
list to obtain the event list to remove from the wait queue.

Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Aaron Durbin <adurbin@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-28 13:51:56 -08:00
Bill Pemberton e3a1a5ec5c kernel/ksysfs.c: remove CONFIG_HOTPLUG ifdefs
Remove conditional code based on CONFIG_HOTPLUG being false.  It's
always on now in preparation of it going away as an option.

Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-11-28 10:33:03 -08:00
Bill Pemberton 3b572b506c sysctl: remove CONFIG_HOTPLUG ifdefs
Remove conditional code based on CONFIG_HOTPLUG being false.  It's
always on now in preparation of it going away as an option.

Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-11-28 10:33:03 -08:00
Frederic Weisbecker fa09205783 cputime: Comment cputime's adjusting code
The reason for the scaling and monotonicity correction performed
by cputime_adjust() may not be immediately clear to the reviewer.

Add some comments to explain what happens there.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
2012-11-28 17:08:20 +01:00
Frederic Weisbecker d37f761dbd cputime: Consolidate cputime adjustment code
task_cputime_adjusted() and thread_group_cputime_adjusted()
essentially share the same code. They just don't use the same
source:

* The first function uses the cputime in the task struct and the
previous adjusted snapshot that ensures monotonicity.

* The second adds the cputime of all tasks in the group and the
previous adjusted snapshot of the whole group from the signal
structure.

Just consolidate the common code that does the adjustment. These
functions just need to fetch the values from the appropriate
source.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
2012-11-28 17:08:10 +01:00
Frederic Weisbecker e80d0a1ae8 cputime: Rename thread_group_times to thread_group_cputime_adjusted
We have thread_group_cputime() and thread_group_times(). The naming
doesn't provide enough information about the difference between
these two APIs.

To lower the confusion, rename thread_group_times() to
thread_group_cputime_adjusted(). This name better suggests that
it's a version of thread_group_cputime() that does some stabilization
on the raw cputime values. ie here: scale on top of CFS runtime
stats and bound lower value for monotonicity.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
2012-11-28 17:07:57 +01:00
Frederic Weisbecker a634f93335 cputime: Move thread_group_cputime() to sched code
thread_group_cputime() is a general cputime API that is not only
used by posix cpu timer. Let's move this helper to sched code.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
2012-11-28 17:07:38 +01:00
Li Zhong fddfb02ad0 cgroup: move list add after list head initilization
2243076ad1 ("cgroup: initialize cgrp->allcg_node in
init_cgroup_housekeeping()") initializes cgrp->allcg_node in
init_cgroup_housekeeping().  Then in init_cgroup_root(), we should
call init_cgroup_housekeeping() before adding it to &root->allcg_list;
otherwise, we are initializing an entry already in a list.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-28 06:02:39 -08:00
Marcelo Tosatti e0b306fef9 time: export time information for KVM pvclock
As suggested by John, export time data similarly to how its
done by vsyscall support. This allows KVM to retrieve necessary
information to implement vsyscall support in KVM guests.

Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-11-27 23:29:12 -02:00
Marcelo Tosatti 582b336ec2 sched: add notifier for cross-cpu migrations
Originally from Jeremy Fitzhardinge.

Acked-by: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-11-27 23:29:09 -02:00
Darren Hart aa10990e02 futex: avoid wake_futex() for a PI futex_q
Dave Jones reported a bug with futex_lock_pi() that his trinity test
exposed.  Sometime between queue_me() and taking the q.lock_ptr, the
lock_ptr became NULL, resulting in a crash.

While futex_wake() is careful to not call wake_futex() on futex_q's with
a pi_state or an rt_waiter (which are either waiting for a
futex_unlock_pi() or a PI futex_requeue()), futex_wake_op() and
futex_requeue() do not perform the same test.

Update futex_wake_op() and futex_requeue() to test for q.pi_state and
q.rt_waiter and abort with -EINVAL if detected.  To ensure any future
breakage is caught, add a WARN() to wake_futex() if the same condition
is true.

This fix has seen 3 hours of testing with "trinity -c futex" on an
x86_64 VM with 4 CPUS.

[akpm@linux-foundation.org: tidy up the WARN()]
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Reported-by: Dave Jones <davej@redat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: John Kacur <jkacur@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-26 17:41:24 -08:00
Chuansheng Liu 8ffeb9b0e6 watchdog: using u64 in get_sample_period()
In get_sample_period(), unsigned long is not enough:

  watchdog_thresh * 2 * (NSEC_PER_SEC / 5)

case1:
  watchdog_thresh is 10 by default, the sample value will be: 0xEE6B2800

case2:
 set watchdog_thresh is 20, the sample value will be: 0x1 DCD6 5000

In case2, we need use u64 to express the sample period.  Otherwise,
changing the threshold thru proc often can not be successful.

Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-26 17:41:24 -08:00
Thomas Gleixner 9c3f9e2816 Merge branch 'fortglx/3.8/time' of git://git.linaro.org/people/jstultz/linux into timers/core
Fix trivial conflicts in: kernel/time/tick-sched.c

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-11-21 20:31:52 +01:00
Tao Ma d0b2fdd2a5 cgroup: remove obsolete guarantee from cgroup_task_migrate.
'guarantee' is already removed from cgroup_task_migrate, so remove
the corresponding comments. Some other typos in cgroup are also
changed.

Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-20 06:44:58 -08:00
Eric W. Biederman 98f842e675 proc: Usable inode numbers for the namespace file descriptors.
Assign a unique proc inode to each namespace, and use that
inode number to ensure we only allocate at most one proc
inode for every namespace in proc.

A single proc inode per namespace allows userspace to test
to see if two processes are in the same namespace.

This has been a long requested feature and only blocked because
a naive implementation would put the id in a global space and
would ultimately require having a namespace for the names of
namespaces, making migration and certain virtualization tricks
impossible.

We still don't have per superblock inode numbers for proc, which
appears necessary for application unaware checkpoint/restart and
migrations (if the application is using namespace file descriptors)
but that is now allowd by the design if it becomes important.

I have preallocated the ipc and uts initial proc inode numbers so
their structures can be statically initialized.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-20 04:19:49 -08:00
Eric W. Biederman c450f371d4 userns: For /proc/self/{uid,gid}_map derive the lower userns from the struct file
To keep things sane in the context of file descriptor passing derive the
user namespace that uids are mapped into from the opener of the file
instead of from current.

When writing to the maps file the lower user namespace must always
be the parent user namespace, or setting the mapping simply does
not make sense.  Enforce that the opener of the file was in
the parent user namespace or the user namespace whose mapping
is being set.

Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-20 04:18:55 -08:00
Eric W. Biederman b2e0d98705 userns: Implement unshare of the user namespace
- Add CLONE_THREAD to the unshare flags if CLONE_NEWUSER is selected
  As changing user namespaces is only valid if all there is only
  a single thread.
- Restore the code to add CLONE_VM if CLONE_THREAD is selected and
  the code to addCLONE_SIGHAND if CLONE_VM is selected.
  Making the constraints in the code clear.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-20 04:18:14 -08:00
Eric W. Biederman cde1975bc2 userns: Implent proc namespace operations
This allows entering a user namespace, and the ability
to store a reference to a user namespace with a bind
mount.

Addition of missing userns_ns_put in userns_install
from Gao feng <gaofeng@cn.fujitsu.com>

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-20 04:18:13 -08:00
Eric W. Biederman 4c44aaafa8 userns: Kill task_user_ns
The task_user_ns function hides the fact that it is getting the user
namespace from struct cred on the task.  struct cred may go away as
soon as the rcu lock is released.  This leads to a race where we
can dereference a stale user namespace pointer.

To make it obvious a struct cred is involved kill task_user_ns.

To kill the race modify the users of task_user_ns to only
reference the user namespace while the rcu lock is held.

Cc: Kees Cook <keescook@chromium.org>
Cc: James Morris <james.l.morris@oracle.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-20 04:17:44 -08:00
Eric W. Biederman bcf58e725d userns: Make create_new_namespaces take a user_ns parameter
Modify create_new_namespaces to explicitly take a user namespace
parameter, instead of implicitly through the task_struct.

This allows an implementation of unshare(CLONE_NEWUSER) where
the new user namespace is not stored onto the current task_struct
until after all of the namespaces are created.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-20 04:17:43 -08:00
Eric W. Biederman 142e1d1d5f userns: Allow unprivileged use of setns.
- Push the permission check from the core setns syscall into
  the setns install methods where the user namespace of the
  target namespace can be determined, and used in a ns_capable
  call.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-20 04:17:42 -08:00
Eric W. Biederman b33c77ef23 userns: Allow unprivileged users to create new namespaces
If an unprivileged user has the appropriate capabilities in their
current user namespace allow the creation of new namespaces.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-20 04:17:41 -08:00
Eric W. Biederman 37657da3c5 userns: Allow setting a userns mapping to your current uid.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-20 04:17:40 -08:00
Dave Jones bf3071f5a0 tracing: Remove unnecessary WARN_ONCE's from tracing_buffers_splice_read
WARN shouldn't be used as a means of communicating failure to a userspace programmer.

Link: http://lkml.kernel.org/r/20120725153908.GA25203@redhat.com

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-19 15:25:09 -05:00
Anton Vorontsov 717a9ef7f3 tracing: Remove unneeded checks from the stack tracer
It seems that 'ftrace_enabled' flag should not be used inside the tracer
functions. The ftrace core is using this flag for internal purposes, and
the flag wasn't meant to be used in tracers' runtime checks.

stack tracer is the only tracer that abusing the flag. So stop it from
serving as a bad example.

Also, there is a local 'stack_trace_disabled' flag in the stack tracer,
which is never updated; so it can be removed as well.

Link: http://lkml.kernel.org/r/1342637761-9655-1-git-send-email-anton.vorontsov@linaro.org

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-19 15:07:13 -05:00
Tejun Heo 0a950f65e1 cgroup: add cgroup->id
With the introduction of generic cgroup hierarchy iterators, css_id is
being phased out.  It was unnecessarily complex, id'ing the wrong
thing (cgroups need IDs, not CSSes) and has other oddities like not
being available at ->css_alloc().

This patch adds cgroup->id, which is a simple per-hierarchy
ida-allocated ID which is assigned before ->css_alloc() and released
after ->css_free().

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
2012-11-19 09:02:12 -08:00
Tejun Heo 033fa1c5f5 cgroup, cpuset: remove cgroup_subsys->post_clone()
Currently CGRP_CPUSET_CLONE_CHILDREN triggers ->post_clone().  Now
that clone_children is cpuset specific, there's no reason to have this
rather odd option activation mechanism in cgroup core.  cpuset can
check the flag from its ->css_allocate() and take the necessary
action.

Move cpuset_post_clone() logic to the end of cpuset_css_alloc() and
remove cgroup_subsys->post_clone().

Loosely based on Glauber's "generalize post_clone into post_create"
patch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Original-patch-by: Glauber Costa <glommer@parallels.com>
Original-patch: <1351686554-22592-2-git-send-email-glommer@parallels.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Glauber Costa <glommer@parallels.com>
2012-11-19 08:13:39 -08:00
Tejun Heo 2260e7fc1f cgroup: s/CGRP_CLONE_CHILDREN/CGRP_CPUSET_CLONE_CHILDREN/
clone_children is only meaningful for cpuset and will stay that way.
Rename the flag to reflect that and update documentation.  Also, drop
clone_children() wrapper in cgroup.c.  The thin wrapper is used only a
few times and one of them will go away soon.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Glauber Costa <glommer@parallels.com>
2012-11-19 08:13:38 -08:00
Tejun Heo 92fb97487a cgroup: rename ->create/post_create/pre_destroy/destroy() to ->css_alloc/online/offline/free()
Rename cgroup_subsys css lifetime related callbacks to better describe
what their roles are.  Also, update documentation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:38 -08:00
Tejun Heo b1929db42f cgroup: allow ->post_create() to fail
There could be cases where controllers want to do initialization
operations which may fail from ->post_create().  This patch makes
->post_create() return -errno to indicate failure and online_css()
relay such failures.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Glauber Costa <glommer@parallels.com>
2012-11-19 08:13:38 -08:00
Tejun Heo 4b8b47eb00 cgroup: update cgroup_create() failure path
cgroup_create() was ignoring failure of cgroupfs files.  Update it
such that, if file creation fails, it rolls back by calling
cgroup_destroy_locked() and returns failure.

Note that error out goto labels are renamed.  The labels are a bit
confusing but will become better w/ later cgroup operation renames.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:38 -08:00
Tejun Heo b8a2df6a5b cgroup: use mutex_trylock() when grabbing i_mutex of a new cgroup directory
All cgroup directory i_mutexes nest outside cgroup_mutex; however, new
directory creation is a special case.  A new cgroup directory is
created while holding cgroup_mutex.  Populating the new directory
requires both the new directory's i_mutex and cgroup_mutex.  Because
all directory i_mutexes nest outside cgroup_mutex, grabbing both
requires releasing cgroup_mutex first, which isn't a good idea as the
new cgroup isn't yet ready to be manipulated by other cgroup
opreations.

This is worked around by grabbing the new directory's i_mutex while
holding cgroup_mutex before making it visible.  As there's no other
user at that point, grabbing the i_mutex under cgroup_mutex can't lead
to deadlock.

cgroup_create_file() was using I_MUTEX_CHILD to tell lockdep not to
worry about the reverse locking order; however, this creates pseudo
locking dependency cgroup_mutex -> I_MUTEX_CHILD, which isn't true -
all directory i_mutexes are still nested outside cgroup_mutex.  This
pseudo locking dependency can lead to spurious lockdep warnings.

Use mutex_trylock() instead.  This will always succeed and lockdep
doesn't create any locking dependency for it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:37 -08:00
Tejun Heo d19e19de48 cgroup: simplify cgroup_load_subsys() failure path
Now that cgroup_unload_subsys() can tell whether the root css is
online or not, we can safely call cgroup_unload_subsys() after idr
init failure in cgroup_load_subsys().

Replace the manual unrolling and invoke cgroup_unload_subsys() on
failure.  This drops cgroup_mutex inbetween but should be safe as the
subsystem will fail try_module_get() and thus can't be mounted
inbetween.  As this means that cgroup_unload_subsys() can be called
before css_sets are rehashed, remove BUG_ON() on %NULL
css_set->subsys[] from cgroup_unload_subsys().

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:37 -08:00
Tejun Heo a31f2d3ff7 cgroup: introduce CSS_ONLINE flag and on/offline_css() helpers
New helpers on/offline_css() respectively wrap ->post_create() and
->pre_destroy() invocations.  online_css() sets CSS_ONLINE after
->post_create() is complete and offline_css() invokes ->pre_destroy()
iff CSS_ONLINE is set and clears it while also handling the temporary
dropping of cgroup_mutex.

This patch doesn't introduce any behavior change at the moment but
will be used to improve cgroup_create() failure path and allow
->post_create() to fail.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:37 -08:00
Tejun Heo 42809dd422 cgroup: separate out cgroup_destroy_locked()
Separate out cgroup_destroy_locked() from cgroup_destroy().  This will
be later used in cgroup_create() failure path.

While at it, add lockdep asserts on i_mutex and cgroup_mutex, and move
@d and @parent assignments to their declarations.

This patch doesn't introduce any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:37 -08:00
Tejun Heo 02ae7486d0 cgroup: fix harmless bugs in cgroup_load_subsys() fail path and cgroup_unload_subsys()
* If idr init fails, cgroup_load_subsys() cleared dummytop->subsys[]
  before calilng ->destroy() making CSS inaccessible to the callback,
  and didn't unlink ss->sibling.  As no modular controller uses
  ->use_id, this doesn't cause any actual problems.

* cgroup_unload_subsys() was forgetting to free idr, call
  ->pre_destroy() and clear ->active.  As there currently is no
  modular controller which uses ->use_id, ->pre_destroy() or ->active,
  this doesn't cause any actual problems.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:37 -08:00
Tejun Heo 648bb56d07 cgroup: lock cgroup_mutex in cgroup_init_subsys()
Make cgroup_init_subsys() grab cgroup_mutex while initializing a
subsystem so that all helpers and callbacks are called under the
context they expect.  This isn't strictly necessary as
cgroup_init_subsys() doesn't race with anybody but will allow adding
lockdep assertions.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:36 -08:00
Tejun Heo b48c6a80a0 cgroup: trivial cleanup for cgroup_init/load_subsys()
Consistently use @css and @dummytop in these two functions instead of
referring to them indirectly.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:36 -08:00
Tejun Heo 38b53abaa3 cgroup: make CSS_* flags bit masks instead of bit positions
Currently, CSS_* flags are defined as bit positions and manipulated
using atomic bitops.  There's no reason to use atomic bitops for them
and bit positions are clunkier to deal with than bit masks.  Make
CSS_* bit masks instead and use the usual C bitwise operators to
access them.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:36 -08:00
Tejun Heo febfcef60d cgroup: cgroup->dentry isn't a RCU pointer
cgroup->dentry is marked and used as a RCU pointer; however, it isn't
one - the final dentry put doesn't go through call_rcu().  cgroup and
dentry share the same RCU freeing rule via synchronize_rcu() in
cgroup_diput() (kfree_rcu() used on cgrp is unnecessary).  If cgrp is
accessible under RCU read lock, so is its dentry and dereferencing
cgrp->dentry doesn't need any further RCU protection or annotation.

While not being accurate, before the previous patch, the RCU accessors
served a purpose as memory barriers - cgroup->dentry used to be
assigned after the cgroup was made visible to cgroup_path(), so the
assignment and dereferencing in cgroup_path() needed the memory
barrier pair.  Now that list_add_tail_rcu() happens after
cgroup->dentry is assigned, this no longer is necessary.

Remove the now unnecessary and misleading RCU annotations from
cgroup->dentry.  To make up for the removal of rcu_dereference_check()
in cgroup_path(), add an explicit rcu_lockdep_assert(), which asserts
the dereference rule of @cgrp, not cgrp->dentry.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:36 -08:00
Tejun Heo 4e139afc22 cgroup: create directory before linking while creating a new cgroup
While creating a new cgroup, cgroup_create() links the newly allocated
cgroup into various places before trying to create its directory.
Because cgroup life-cycle is tied to the vfs objects, this makes it
impossible to use cgroup_rmdir() for rolling back creation - the
removal logic depends on having full vfs objects.

This patch moves directory creation above linking and collect linking
operations to one place.  This allows directory creation failure to
share error exit path with css allocation failures and any failure
sites afterwards (to be added later) can use cgroup_rmdir() logic to
undo creation.

Note that this also makes the memory barriers around cgroup->dentry,
which currently is misleadingly using RCU operations, unnecessary.
This will be handled in the next patch.

While at it, locking BUG_ON() on i_mutex is converted to
lockdep_assert_held().

v2: Patch originally removed %NULL dentry check in cgroup_path();
    however, Li pointed out that this patch doesn't make it
    unnecessary as ->create() may call cgroup_path().  Drop the
    change for now.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:36 -08:00
Tejun Heo 28fd6f30ac cgroup: open-code cgroup_create_dir()
The operation order of cgroup creation is about to change and
cgroup_create_dir() is more of a hindrance than a proper abstraction.
Open-code it by moving the parent nlink adjustment next to self nlink
adjustment in cgroup_create_file() and the rest to cgroup_create().

This patch doesn't introduce any behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:36 -08:00
Tejun Heo 2243076ad1 cgroup: initialize cgrp->allcg_node in init_cgroup_housekeeping()
Not strictly necessary but it's annoying to have uninitialized
list_head around.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19 08:13:35 -08:00
Tejun Heo 175431635e cgroup: remove incorrect dget/dput() pair in cgroup_create_dir()
cgroup_create_dir() does weird dancing with dentry refcnt.  On
success, it gets and then puts it achieving nothing.  On failure, it
puts but there isn't no matching get anywhere leading to the following
oops if cgroup_create_file() fails for whatever reason.

  ------------[ cut here ]------------
  kernel BUG at /work/os/work/fs/dcache.c:552!
  invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
  Modules linked in:
  CPU 2
  Pid: 697, comm: mkdir Not tainted 3.7.0-rc4-work+ #3 Bochs Bochs
  RIP: 0010:[<ffffffff811d9c0c>]  [<ffffffff811d9c0c>] dput+0x1dc/0x1e0
  RSP: 0018:ffff88001a3ebef8  EFLAGS: 00010246
  RAX: 0000000000000000 RBX: ffff88000e5b1ef8 RCX: 0000000000000403
  RDX: 0000000000000303 RSI: 2000000000000000 RDI: ffff88000e5b1f58
  RBP: ffff88001a3ebf18 R08: ffffffff82c76960 R09: 0000000000000001
  R10: ffff880015022080 R11: ffd9bed70f48a041 R12: 00000000ffffffea
  R13: 0000000000000001 R14: ffff88000e5b1f58 R15: 00007fff57656d60
  FS:  00007ff05fcb3800(0000) GS:ffff88001fd00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00000000004046f0 CR3: 000000001315f000 CR4: 00000000000006e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
  Process mkdir (pid: 697, threadinfo ffff88001a3ea000, task ffff880015022080)
  Stack:
   ffff88001a3ebf48 00000000ffffffea 0000000000000001 0000000000000000
   ffff88001a3ebf38 ffffffff811cc889 0000000000000001 ffff88000e5b1ef8
   ffff88001a3ebf68 ffffffff811d1fc9 ffff8800198d7f18 ffff880019106ef8
  Call Trace:
   [<ffffffff811cc889>] done_path_create+0x19/0x50
   [<ffffffff811d1fc9>] sys_mkdirat+0x59/0x80
   [<ffffffff811d2009>] sys_mkdir+0x19/0x20
   [<ffffffff81be1e02>] system_call_fastpath+0x16/0x1b
  Code: 00 48 8d 90 18 01 00 00 48 89 93 c0 00 00 00 4c 89 a0 18 01 00 00 48 8b 83 a0 00 00 00 83 80 28 01 00 00 01 e8 e6 6f a0 00 eb 92 <0f> 0b 66 90 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 49 89 fe 41
  RIP  [<ffffffff811d9c0c>] dput+0x1dc/0x1e0
   RSP <ffff88001a3ebef8>
  ---[ end trace 1277bcfd9561ddb0 ]---

Fix it by dropping the unnecessary dget/dput() pair.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
2012-11-19 08:13:35 -08:00
Frederic Weisbecker 1017769bd0 vtime: No need to disable irqs on vtime_account()
vtime_account() is only called from irq entry. irqs
are always disabled at this point so we can safely
remove the irq disabling guards on that function.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-11-19 16:41:41 +01:00
Frederic Weisbecker e3942ba040 vtime: Consolidate a bit the ctx switch code
On ia64 and powerpc, vtime context switch only consists
in flushing system and user pending time, plus a few
arch housekeeping.

Consolidate that into a generic implementation. s390 is
a special case because pending user and system time accounting
there is hard to dissociate. So it's keeping its own implementation.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-11-19 16:41:32 +01:00
Frederic Weisbecker fd25b4c2f2 vtime: Remove the underscore prefix invasion
Prepending irq-unsafe vtime APIs with underscores was actually
a bad idea as the result is a big mess in the API namespace that
is even waiting to be further extended. Also these helpers
are always called from irq safe callers except kvm. Just
provide a vtime_account_system_irqsafe() for this specific
case so that we can remove the underscore prefix on other
vtime functions.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-11-19 16:40:16 +01:00
Eric W. Biederman 5eaf563e53 userns: Allow unprivileged users to create user namespaces.
Now that we have been through every permission check in the kernel
having uid == 0 and gid == 0 in your local user namespace no
longer adds any special privileges.  Even having a full set
of caps in your local user namespace is safe because capabilies
are relative to your local user namespace, and do not confer
unexpected privileges.

Over the long term this should allow much more of the kernels
functionality to be safely used by non-root users.  Functionality
like unsharing the mount namespace that is only unsafe because
it can fool applications whose privileges are raised when they
are executed.  Since those applications have no privileges in
a user namespaces it becomes safe to spoof and confuse those
applications all you want.

Those capabilities will still need to be enabled carefully because
we may still need things like rlimits on the number of unprivileged
mounts but that is to avoid DOS attacks not to avoid fooling root
owned processes.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-19 05:59:24 -08:00
Eric W. Biederman 771b137168 vfs: Add a user namespace reference from struct mnt_namespace
This will allow for support for unprivileged mounts in a new user namespace.

Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-19 05:59:19 -08:00
Eric W. Biederman 50804fe373 pidns: Support unsharing the pid namespace.
Unsharing of the pid namespace unlike unsharing of other namespaces
does not take affect immediately.  Instead it affects the children
created with fork and clone.  The first of these children becomes the init
process of the new pid namespace, the rest become oddball children
of pid 0.  From the point of view of the new pid namespace the process
that created it is pid 0, as it's pid does not map.

A couple of different semantics were considered but this one was
settled on because it is easy to implement and it is usable from
pam modules.  The core reasons for the existence of unshare.

I took a survey of the callers of pam modules and the following
appears to be a representative sample of their logic.
{
	setup stuff include pam
	child = fork();
	if (!child) {
		setuid()
                exec /bin/bash
        }
        waitpid(child);

        pam and other cleanup
}

As you can see there is a fork to create the unprivileged user
space process.  Which means that the unprivileged user space
process will appear as pid 1 in the new pid namespace.  Further
most login processes do not cope with extraneous children which
means shifting the duty of reaping extraneous child process to
the creator of those extraneous children makes the system more
comprehensible.

The practical reason for this set of pid namespace semantics is
that it is simple to implement and verify they work correctly.
Whereas an implementation that requres changing the struct
pid on a process comes with a lot more races and pain.  Not
the least of which is that glibc caches getpid().

These semantics are implemented by having two notions
of the pid namespace of a proces.  There is task_active_pid_ns
which is the pid namspace the process was created with
and the pid namespace that all pids are presented to
that process in.  The task_active_pid_ns is stored
in the struct pid of the task.

Then there is the pid namespace that will be used for children
that pid namespace is stored in task->nsproxy->pid_ns.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-19 05:59:16 -08:00
Eric W. Biederman 1c4042c29b pidns: Consolidate initialzation of special init task state
Instead of setting child_reaper and SIGNAL_UNKILLABLE one way
for the system init process, and another way for pid namespace
init processes test pid->nr == 1 and use the same code for both.

For the global init this results in SIGNAL_UNKILLABLE being set
much earlier in the initialization process.

This is a small cleanup and it paves the way for allowing unshare and
enter of the pid namespace as that path like our global init also will
not set CLONE_NEWPID.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-19 05:59:15 -08:00
Eric W. Biederman 57e8391d32 pidns: Add setns support
- Pid namespaces are designed to be inescapable so verify that the
  passed in pid namespace is a child of the currently active
  pid namespace or the currently active pid namespace itself.

  Allowing the currently active pid namespace is important so
  the effects of an earlier setns can be cancelled.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-19 05:59:14 -08:00
Eric W. Biederman 225778d68d pidns: Deny strange cases when creating pid namespaces.
task_active_pid_ns(current) != current->ns_proxy->pid_ns will
soon be allowed to support unshare and setns.

The definition of creating a child pid namespace when
task_active_pid_ns(current) != current->ns_proxy->pid_ns could be that
we create a child pid namespace of current->ns_proxy->pid_ns.  However
that leads to strange cases like trying to have a single process be
init in multiple pid namespaces, which is racy and hard to think
about.

The definition of creating a child pid namespace when
task_active_pid_ns(current) != current->ns_proxy->pid_ns could be that
we create a child pid namespace of task_active_pid_ns(current).  While
that seems less racy it does not provide any utility.

Therefore define the semantics of creating a child pid namespace when
task_active_pid_ns(current) != current->ns_proxy->pid_ns to be that the
pid namespace creation fails.  That is easy to implement and easy
to think about.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-19 05:59:13 -08:00
Eric W. Biederman af4b8a83ad pidns: Wait in zap_pid_ns_processes until pid_ns->nr_hashed == 1
Looking at pid_ns->nr_hashed is a bit simpler and it works for
disjoint process trees that an unshare or a join of a pid_namespace
may create.

Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-19 05:59:12 -08:00
Eric W. Biederman 5e1182deb8 pidns: Don't allow new processes in a dead pid namespace.
Set nr_hashed to -1 just before we schedule the work to cleanup proc.
Test nr_hashed just before we hash a new pid and if nr_hashed is < 0
fail.

This guaranteees that processes never enter a pid namespaces after we
have cleaned up the state to support processes in a pid namespace.

Currently sending SIGKILL to all of the process in a pid namespace as
init exists gives us this guarantee but we need something a little
stronger to support unsharing and joining a pid namespace.

Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-19 05:59:11 -08:00
Eric W. Biederman 0a01f2cc39 pidns: Make the pidns proc mount/umount logic obvious.
Track the number of pids in the proc hash table.  When the number of
pids goes to 0 schedule work to unmount the kernel mount of proc.

Move the mount of proc into alloc_pid when we allocate the pid for
init.

Remove the surprising calls of pid_ns_release proc in fork and
proc_flush_task.  Those code paths really shouldn't know about proc
namespace implementation details and people have demonstrated several
times that finding and understanding those code paths is difficult and
non-obvious.

Because of the call path detach pid is alwasy called with the
rtnl_lock held free_pid is not allowed to sleep, so the work to
unmounting proc is moved to a work queue.  This has the side benefit
of not blocking the entire world waiting for the unnecessary
rcu_barrier in deactivate_locked_super.

In the process of making the code clear and obvious this fixes a bug
reported by Gao feng <gaofeng@cn.fujitsu.com> where we would leak a
mount of proc during clone(CLONE_NEWPID|CLONE_NEWNET) if copy_pid_ns
succeeded and copy_net_ns failed.

Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-19 05:59:10 -08:00
Eric W. Biederman 17cf22c33e pidns: Use task_active_pid_ns where appropriate
The expressions tsk->nsproxy->pid_ns and task_active_pid_ns
aka ns_of_pid(task_pid(tsk)) should have the same number of
cache line misses with the practical difference that
ns_of_pid(task_pid(tsk)) is released later in a processes life.

Furthermore by using task_active_pid_ns it becomes trivial
to write an unshare implementation for the the pid namespace.

So I have used task_active_pid_ns everywhere I can.

In fork since the pid has not yet been attached to the
process I use ns_of_pid, to achieve the same effect.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-19 05:59:09 -08:00
Eric W. Biederman 49f4d8b93c pidns: Capture the user namespace and filter ns_last_pid
- Capture the the user namespace that creates the pid namespace
- Use that user namespace to test if it is ok to write to
  /proc/sys/kernel/ns_last_pid.

Zhao Hongjiang <zhaohongjiang@huawei.com> noticed I was missing a put_user_ns
in when destroying a pid_ns.  I have foloded his patch into this one
so that bisects will work properly.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-19 05:57:31 -08:00
Eric W. Biederman 038e7332b8 userns: make each net (net_ns) belong to a user_ns
The user namespace which creates a new network namespace owns that
namespace and all resources created in it.  This way we can target
capability checks for privileged operations against network resources to
the user_ns which created the network namespace in which the resource
lives.  Privilege to the user namespace which owns the network
namespace, or any parent user namespace thereof, provides the same
privilege to the network resource.

This patch is reworked from a version originally by
Serge E. Hallyn <serge.hallyn@canonical.com>

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-18 22:46:23 -08:00
Eric W. Biederman d328b83682 userns: make each net (net_ns) belong to a user_ns
The user namespace which creates a new network namespace owns that
namespace and all resources created in it.  This way we can target
capability checks for privileged operations against network resources to
the user_ns which created the network namespace in which the resource
lives.  Privilege to the user namespace which owns the network
namespace, or any parent user namespace thereof, provides the same
privilege to the network resource.

This patch is reworked from a version originally by
Serge E. Hallyn <serge.hallyn@canonical.com>

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-11-18 20:30:55 -05:00
Ingo Molnar ec05a2311c Merge branch 'sched/urgent' into sched/core
Merge in fixes before we queue up dependent bits, to avoid conflicts.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-11-18 09:34:44 +01:00
David S. Miller 67f4efdce7 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Minor line offset auto-merges.

Signed-off-by: David S. Miller <davem@davemloft.net>
2012-11-17 22:00:43 -05:00
Greg Kroah-Hartman 1e619a1bf9 Merge 3.7-rc6 into tty-next 2012-11-16 18:26:00 -08:00
Paul E. McKenney 4e79752c25 sched: Mark RCU reader in sched_show_task()
When sched_show_task() is invoked from try_to_freeze_tasks(), there is
no RCU read-side critical section, resulting in the following splat:

[  125.780730] ===============================
[  125.780766] [ INFO: suspicious RCU usage. ]
[  125.780804] 3.7.0-rc3+ #988 Not tainted
[  125.780838] -------------------------------
[  125.780875] /home/rafael/src/linux/kernel/sched/core.c:4497 suspicious rcu_dereference_check() usage!
[  125.780946]
[  125.780946] other info that might help us debug this:
[  125.780946]
[  125.781031]
[  125.781031] rcu_scheduler_active = 1, debug_locks = 0
[  125.781087] 4 locks held by s2ram/4211:
[  125.781120]  #0:  (&buffer->mutex){+.+.+.}, at: [<ffffffff811e2acf>] sysfs_write_file+0x3f/0x160
[  125.781233]  #1:  (s_active#94){.+.+.+}, at: [<ffffffff811e2b58>] sysfs_write_file+0xc8/0x160
[  125.781339]  #2:  (pm_mutex){+.+.+.}, at: [<ffffffff81090a81>] pm_suspend+0x81/0x230
[  125.781439]  #3:  (tasklist_lock){.?.?..}, at: [<ffffffff8108feed>] try_to_freeze_tasks+0x2cd/0x3f0
[  125.781543]
[  125.781543] stack backtrace:
[  125.781584] Pid: 4211, comm: s2ram Not tainted 3.7.0-rc3+ #988
[  125.781632] Call Trace:
[  125.781662]  [<ffffffff810a3c73>] lockdep_rcu_suspicious+0x103/0x140
[  125.781719]  [<ffffffff8107cf21>] sched_show_task+0x121/0x180
[  125.781770]  [<ffffffff8108ffb4>] try_to_freeze_tasks+0x394/0x3f0
[  125.781823]  [<ffffffff810903b5>] freeze_kernel_threads+0x25/0x80
[  125.781876]  [<ffffffff81090b65>] pm_suspend+0x165/0x230
[  125.781924]  [<ffffffff8108fa29>] state_store+0x99/0x100
[  125.781975]  [<ffffffff812f5867>] kobj_attr_store+0x17/0x20
[  125.782038]  [<ffffffff811e2b71>] sysfs_write_file+0xe1/0x160
[  125.782091]  [<ffffffff811667a6>] vfs_write+0xc6/0x180
[  125.782138]  [<ffffffff81166ada>] sys_write+0x5a/0xa0
[  125.782185]  [<ffffffff812ff6ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[  125.782242]  [<ffffffff81669dd2>] system_call_fastpath+0x16/0x1b

This commit therefore adds the needed RCU read-side critical section.

Reported-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-16 10:05:58 -08:00
Paul E. McKenney c635a4e1c2 rcu: Separate accounting of callbacks from callback-free CPUs
Currently, callback invocations from callback-free CPUs are accounted to
the CPU that registered the callback, but using the same field that is
used for normal callbacks.  This makes it impossible to determine from
debugfs output whether callbacks are in fact being diverted.  This commit
therefore adds a separate ->n_nocbs_invoked field in the rcu_data structure
in which diverted callback invocations are counted.  RCU's debugfs tracing
still displays normal callback invocations using ci=, but displayed
diverted callbacks with nci=.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-16 10:05:57 -08:00
Paul E. McKenney 3fbfbf7a3b rcu: Add callback-free CPUs
RCU callback execution can add significant OS jitter and also can
degrade both scheduling latency and, in asymmetric multiprocessors,
energy efficiency.  This commit therefore adds the ability for selected
CPUs ("rcu_nocbs=" boot parameter) to have their callbacks offloaded
to kthreads.  If the "rcu_nocb_poll" boot parameter is also specified,
these kthreads will do polling, removing the need for the offloaded
CPUs to do wakeups.  At least one CPU must be doing normal callback
processing: currently CPU 0 cannot be selected as a no-CBs CPU.
In addition, attempts to offline the last normal-CBs CPU will fail.

This feature was inspired by Jim Houston's and Joe Korty's JRCU, and
this commit includes fixes to problems located by Fengguang Wu's
kbuild test robot.

[ paulmck: Added gfp.h include file as suggested by Fengguang Wu. ]

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-16 10:05:56 -08:00
Paul E. McKenney aac1cda34b Merge branches 'urgent.2012.10.27a', 'doc.2012.11.16a', 'fixes.2012.11.13a', 'srcu.2012.10.27a', 'stall.2012.11.13a', 'tracing.2012.11.08a' and 'idle.2012.10.24a' into HEAD
urgent.2012.10.27a: Fix for RCU user-mode transition (already in -tip).

doc.2012.11.08a: Documentation updates, most notably codifying the
	memory-barrier guarantees inherent to grace periods.

fixes.2012.11.13a: Miscellaneous fixes.

srcu.2012.10.27a: Allow statically allocated and initialized srcu_struct
	structures (courtesy of Lai Jiangshan).

stall.2012.11.13a: Add more diagnostic information to RCU CPU stall
	warnings, also decrease from 60 seconds to 21 seconds.

hotplug.2012.11.08a: Minor updates to CPU hotplug handling.

tracing.2012.11.08a: Improved debugfs tracing, courtesy of Michael Wang.

idle.2012.10.24a: Updates to RCU idle/adaptive-idle handling, including
	a boot parameter that maps normal grace periods to expedited.

Resolved conflict in kernel/rcutree.c due to side-by-side change.
2012-11-16 09:59:58 -08:00
Oleg Nesterov 32cdba1e05 uprobes: Use percpu_rw_semaphore to fix register/unregister vs dup_mmap() race
This was always racy, but 268720903f
"uprobes: Rework register_for_each_vma() to make it O(n)" should be
blamed anyway, it made everything worse and I didn't notice.

register/unregister call build_map_info() and then do install/remove
breakpoint for every mm which mmaps inode/offset. This can obviously
race with fork()->dup_mmap() in between and we can miss the child.

uprobe_register() could be easily fixed but unregister is much worse,
the new mm inherits "int3" from parent and there is no way to detect
this if uprobe goes away.

So this patch simply adds percpu_down_read/up_read around dup_mmap(),
and percpu_down_write/up_write into register_for_each_vma().

This adds 2 new hooks into dup_mmap() but we can kill uprobe_dup_mmap()
and fold it into uprobe_end_dup_mmap().

Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2012-11-16 14:52:51 +01:00
Hiraku Toyooka d60da506cb tracing: Add a resize function to make one buffer equivalent to another buffer
Trace buffer size is now per-cpu, so that there are the following two
patterns in resizing of buffers.

  (1) resize per-cpu buffers to same given size
  (2) resize per-cpu buffers to another trace_array's buffer size
      for each CPU (such as preparing the max_tr which is equivalent
      to the global_trace's size)

__tracing_resize_ring_buffer() can be used for (1), and had
implemented (2) inside it for resetting the global_trace to the
original size.

(2) was also implemented in another place. So this patch assembles
them in a new function - resize_buffer_duplicate_size().

Link: http://lkml.kernel.org/r/20121017025616.2627.91226.stgit@falsita

Signed-off-by: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-15 17:10:21 -05:00
Dan Carpenter 70f77b3f7e ftrace: Clear bits properly in reset_iter_read()
There is a typo here where '&' is used instead of '|' and it turns the
statement into a noop.  The original code is equivalent to:

	iter->flags &= ~((1 << 2) & (1 << 4));

Link: http://lkml.kernel.org/r/20120609161027.GD6488@elgon.mountain

Cc: stable@vger.kernel.org # all of them
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-15 16:10:17 -05:00
Davidlohr Bueso 8316bd72c0 PM / Hibernate: use rb_entry
Since the software suspend extents are organized in an rbtree, use rb_entry
instead of container_of, as it is semantically more appropriate in order to
get a node as it is iterated.

Signed-off-by: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-15 00:37:08 +01:00
Daniel Walter 883ee4f79d PM / sysfs: replace strict_str* with kstrto*
Replace strict_strtoul() with kstrtoul() in pm_async_store() and
pm_qos_power_write().

[rjw: Modified subject and changelog.]

Signed-off-by: Daniel Walter <sahne@0x90.at>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-15 00:37:08 +01:00
Youquan Song 69a37beabf cpuidle: Quickly notice prediction failure for repeat mode
The prediction for future is difficult and when the cpuidle governor prediction
fails and govenor possibly choose the shallower C-state than it should. How to
quickly notice and find the failure becomes important for power saving.

cpuidle menu governor has a method to predict the repeat pattern if there are 8
C-states residency which are continuous and the same or very close, so it will
predict the next C-states residency will keep same residency time.

There is a real case that turbostat utility (tools/power/x86/turbostat)
at kernel 3.3 or early. turbostat utility will read 10 registers one by one at
Sandybridge, so it will generate 10 IPIs to wake up idle CPUs. So cpuidle menu
 governor will predict it is repeat mode and there is another IPI wake up idle
 CPU soon, so it keeps idle CPU stay at C1 state even though CPU is totally
idle. However, in the turbostat, following 10 registers reading is sleep 5
seconds by default, so the idle CPU will keep at C1 for a long time though it is
 idle until break event occurs.
In a idle Sandybridge system, run "./turbostat -v", we will notice that deep
C-state dangles between "70% ~ 99%". After patched the kernel, we will notice
deep C-state stays at >99.98%.

In the patch, a timer is added when menu governor detects a repeat mode and
choose a shallow C-state. The timer is set to a time out value that greater
than predicted time, and we conclude repeat mode prediction failure if timer is
triggered. When repeat mode happens as expected, the timer is not triggered
and CPU waken up from C-states and it will cancel the timer initiatively.
When repeat mode does not happen, the timer will be time out and menu governor
will quickly notice that the repeat mode prediction fails and then re-evaluates
deeper C-states possibility.

Below is another case which will clearly show the patch much benefit:

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sys/time.h>
#include <time.h>
#include <pthread.h>

volatile int * shutdown;
volatile long * count;
int delay = 20;
int loop = 8;

void usage(void)
{
	fprintf(stderr,
		"Usage: idle_predict [options]\n"
		"  --help	-h  Print this help\n"
		"  --thread	-n  Thread number\n"
		"  --loop     	-l  Loop times in shallow Cstate\n"
		"  --delay	-t  Sleep time (uS)in shallow Cstate\n");
}

void *simple_loop() {
	int idle_num = 1;
	while (!(*shutdown)) {
		*count = *count + 1;

		if (idle_num % loop)
			usleep(delay);
		else {
			/* sleep 1 second */
			usleep(1000000);
			idle_num = 0;
		}
		idle_num++;
	}

}

static void sighand(int sig)
{
	*shutdown = 1;
}

int main(int argc, char *argv[])
{
	sigset_t sigset;
	int signum = SIGALRM;
	int i, c, er = 0, thread_num = 8;
	pthread_t pt[1024];

	static char optstr[] = "n:l:t:h:";

	while ((c = getopt(argc, argv, optstr)) != EOF)
		switch (c) {
			case 'n':
				thread_num = atoi(optarg);
				break;
			case 'l':
				loop = atoi(optarg);
				break;
			case 't':
				delay = atoi(optarg);
				break;
			case 'h':
			default:
				usage();
				exit(1);
		}

	printf("thread=%d,loop=%d,delay=%d\n",thread_num,loop,delay);
	count = malloc(sizeof(long));
	shutdown = malloc(sizeof(int));
	*count = 0;
	*shutdown = 0;

	sigemptyset(&sigset);
	sigaddset(&sigset, signum);
	sigprocmask (SIG_BLOCK, &sigset, NULL);
	signal(SIGINT, sighand);
	signal(SIGTERM, sighand);

	for(i = 0; i < thread_num ; i++)
		pthread_create(&pt[i], NULL, simple_loop, NULL);

	for (i = 0; i < thread_num; i++)
		pthread_join(pt[i], NULL);

	exit(0);
}

Get powertop V2 from git://github.com/fenrus75/powertop, build powertop.
After build the above test application, then run it.
Test plaform can be Intel Sandybridge or other recent platforms.
#./idle_predict -l 10 &
#./powertop

We will find that deep C-state will dangle between 40%~100% and much time spent
on C1 state. It is because menu governor wrongly predict that repeat mode
is kept, so it will choose the C1 shallow C-state even though it has chance to
sleep 1 second in deep C-state.

While after patched the kernel, we find that deep C-state will keep >99.6%.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-15 00:34:19 +01:00
Yasuaki Ishimatsu 5e5041f352 ACPI / processor: prevent cpu from becoming online
Even if acpi_processor_handle_eject() offlines cpu, there is a chance
to online the cpu after that. So the patch closes the window by using
get/put_online_cpus().

Why does the patch change _cpu_up() logic?

The patch cares the race of hot-remove cpu and _cpu_up(). If the patch
does not change it, there is the following race.

hot-remove cpu                         |  _cpu_up()
------------------------------------- ------------------------------------
call acpi_processor_handle_eject()     |
     call cpu_down()                   |
     call get_online_cpus()            |
                                       | call cpu_hotplug_begin() and stop here
     call arch_unregister_cpu()        |
     call acpi_unmap_lsapic()          |
     call put_online_cpus()            |
                                       | start and continue _cpu_up()
     return acpi_processor_remove()    |
continue hot-remove the cpu            |

So _cpu_up() can continue to itself. And hot-remove cpu can also continue
itself. If the patch changes _cpu_up() logic, the race disappears as below:

hot-remove cpu                         | _cpu_up()
-----------------------------------------------------------------------
call acpi_processor_handle_eject()     |
     call cpu_down()                   |
     call get_online_cpus()            |
                                       | call cpu_hotplug_begin() and stop here
     call arch_unregister_cpu()        |
     call acpi_unmap_lsapic()          |
          cpu's cpu_present is set     |
          to false by set_cpu_present()|
     call put_online_cpus()            |
                                       | start _cpu_up()
                                       | check cpu_present() and return -EINVAL
     return acpi_processor_remove()    |
continue hot-remove the cpu            |

Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-15 00:16:00 +01:00
Greg Kroah-Hartman 54d5f88f25 Merge v3.7-rc5 into tty-next
This pulls in the 3.7-rc5 fixes into tty-next to make it easier to test.
2012-11-14 12:30:12 -08:00
Fenghua Yu 6e32d479db kernel/cpu.c: Add comment for priority in cpu_hotplug_pm_callback
cpu_hotplug_pm_callback should have higher priority than
bsp_pm_callback which depends on cpu_hotplug_pm_callback to disable cpu hotplug
to avoid race during bsp online checking.

This is to hightlight the priorities between the two callbacks in case people
may overlook the order.

Ideally the priorities should be defined in macro/enum instead of fixed values.
To do that, a seperate patchset may be pushed which will touch serveral other
generic files and is out of scope of this patchset.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1352835171-3958-7-git-send-email-fenghua.yu@intel.com
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2012-11-14 09:39:50 -08:00
Rabin Vincent 65b6ecc038 uprobes: Flush cache after xol write
Flush the cache so that the instructions written to the XOL area are
visible.

Signed-off-by: Rabin Vincent <rabin@rab.in>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2012-11-14 18:32:24 +01:00
Ingo Molnar a7a0aaa17a Linux 3.7-rc5
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Merge tag 'v3.7-rc5' into sched/core

Merge Linux 3.7-rc5, to pick up fixes.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-11-14 08:49:49 +01:00
Paul E. McKenney 351573a86d rcu: Fix TINY_RCU rcu_is_cpu_rrupt_from_idle check
The rcu_is_cpu_rrupt_from_idle() needs to allow for one interrupt level
from the idle loop, but TINY_RCU checks for a call from the idle loop
itself.  This commit fixes this issue.

Reported-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-13 14:08:34 -08:00
Paul E. McKenney f0a0e6f282 rcu: Clarify memory-ordering properties of grace-period primitives
This commit explicitly states the memory-ordering properties of the
RCU grace-period primitives.  Although these properties were in some
sense implied by the fundmental property of RCU ("a grace period must
wait for all pre-existing RCU read-side critical sections to complete"),
stating it explicitly will be a great labor-saving device.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
2012-11-13 14:08:23 -08:00
Paul E. McKenney 67afeed2ca rcu: Add new rcutorture module parameters to start/end test messages
Several new rcutorture module parameters have been added, but are not
printed to the console at the beginning and end of tests, which makes
it difficult to reproduce a prior test.  This commit therefore adds
these new module parameters to the list printed at the beginning and
the end of the tests.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-13 14:08:22 -08:00
Eric Dumazet 878d7439d0 rcu: Fix batch-limit size problem
Commit 29c00b4a1d (rcu: Add event-tracing for RCU callback
invocation) added a regression in rcu_do_batch()

Under stress, RCU is supposed to allow to process all items in queue,
instead of a batch of 10 items (blimit), but an integer overflow makes
the effective limit being 1.  So, unless there is frequent idle periods
(during which RCU ignores batch limits), RCU can be forced into a
state where it cannot keep up with the callback-generation rate,
eventually resulting in OOM.

This commit therefore converts a few variables in rcu_do_batch() from
int to long to fix this problem, along with the module parameters
controlling the batch limits.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # 3.2 +
2012-11-13 14:07:57 -08:00
Yoshihiro YUNOMAE 11043d8b12 tracing: Show raw time stamp on stats per cpu using counter or tsc mode for trace_clock
Show raw time stamp values for stats per cpu if you choose counter or tsc mode
for trace_clock. Although a unit of tracing time stamp is nsec in local or global mode,
the units in counter and TSC mode are tracing counter and cycles respectively.
Link: http://lkml.kernel.org/r/1352837903-32191-3-git-send-email-dhsharp@google.com

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: David Sharp <dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-13 15:49:11 -05:00
David Sharp 8be0709f10 tracing: Format non-nanosec times from tsc clock without a decimal point.
With the addition of the "tsc" clock, formatting timestamps to look like
fractional seconds is misleading. Mark clocks as either in nanoseconds or
not, and format non-nanosecond timestamps as decimal integers.

Tested:
$ cd /sys/kernel/debug/tracing/
$ cat trace_clock
[local] global tsc
$ echo sched_switch > set_event
$ echo 1 > tracing_on ; sleep 0.0005 ; echo 0 > tracing_on
$ cat trace
          <idle>-0     [000]  6330.555552: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=bash next_pid=29964 next_prio=120
           sleep-29964 [000]  6330.555628: sched_switch: prev_comm=bash prev_pid=29964 prev_prio=120 prev_state=S ==> next_comm=swapper next_pid=0 next_prio=120
  ...
$ echo 1 > options/latency-format
$ cat trace
  <idle>-0       0 4104553247us+: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=bash next_pid=29964 next_prio=120
   sleep-29964   0 4104553322us+: sched_switch: prev_comm=bash prev_pid=29964 prev_prio=120 prev_state=S ==> next_comm=swapper next_pid=0 next_prio=120
  ...
$ echo tsc > trace_clock
$ cat trace
$ echo 1 > tracing_on ; sleep 0.0005 ; echo 0 > tracing_on
$ echo 0 > options/latency-format
$ cat trace
          <idle>-0     [000] 16490053398357: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=bash next_pid=31128 next_prio=120
           sleep-31128 [000] 16490053588518: sched_switch: prev_comm=bash prev_pid=31128 prev_prio=120 prev_state=S ==> next_comm=swapper next_pid=0 next_prio=120
  ...
echo 1 > options/latency-format
$ cat trace
  <idle>-0       0 91557653238+: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=bash next_pid=31128 next_prio=120
   sleep-31128   0 91557843399+: sched_switch: prev_comm=bash prev_pid=31128 prev_prio=120 prev_state=S ==> next_comm=swapper next_pid=0 next_prio=120
  ...

v2:
Move arch-specific bits out of generic code.
v4:
Fix x86_32 build due to 64-bit division.

Google-Bug-Id: 6980623
Link: http://lkml.kernel.org/r/1352837903-32191-2-git-send-email-dhsharp@google.com

Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: David Sharp <dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-13 15:48:40 -05:00
David Sharp 8cbd9cc625 tracing,x86: Add a TSC trace_clock
In order to promote interoperability between userspace tracers and ftrace,
add a trace_clock that reports raw TSC values which will then be recorded
in the ring buffer. Userspace tracers that also record TSCs are then on
exactly the same time base as the kernel and events can be unambiguously
interlaced.

Tested: Enabled a tracepoint and the "tsc" trace_clock and saw very large
timestamp values.

v2:
Move arch-specific bits out of generic code.
v3:
Rename "x86-tsc", cleanups
v7:
Generic arch bits in Kbuild.

Google-Bug-Id: 6980623
Link: http://lkml.kernel.org/r/1352837903-32191-1-git-send-email-dhsharp@google.com

Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Signed-off-by: David Sharp <dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-13 15:48:27 -05:00
John Stultz d6ad418763 time: Kill xtime_lock, replacing it with jiffies_lock
Now that timekeeping is protected by its own locks, rename
the xtime_lock to jifffies_lock to better describe what it
protects.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-11-13 14:08:23 -05:00
Lars-Peter Clausen f95a985781 time/jiffies: Make clocksource_jiffies static
Commit f1b8274 ("clocksource: Cleanup clocksource selection") removed all
external references to clocksource_jiffies so there is no need to have the
symbol globally visible.

Fixes the following sparse warning:
  CHECK   kernel/time/jiffies.c kernel/time/jiffies.c:61:20: warning: symbol 'clocksource_jiffies' was not declared. Should it be static?

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-11-13 14:04:51 -05:00
Linus Torvalds b0db954c04 Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull futex fix from Thomas Gleixner:
 "Single fix for a long standing futex race when taking over a futex
  whose owner died.  You can end up with two owners, which violates
  quite some rules."

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Handle futex_pi OWNER_DIED take over correctly
2012-11-12 17:02:21 -08:00
Thomas Gleixner 04aa530ec0 genirq: Always force thread affinity
Sankara reported that the genirq core code fails to adjust the
affinity of an interrupt thread in several cases:

 1) On request/setup_irq() the call to setup_affinity() happens before
    the new action is registered, so the new thread is not notified.

 2) For secondary shared interrupts nothing notifies the new thread to
    change its affinity.

 3) Interrupts which have the IRQ_NO_BALANCE flag set are not moving
    the thread either.

Fix this by setting the thread affinity flag right on thread creation
time. This ensures that under all circumstances the thread moves to
the right place. Requires a check in irq_thread_check_affinity for an
existing affinity mask (CONFIG_CPU_MASK_OFFSTACK=y)

Reported-and-tested-by: Sankara Muthukrishnan <sankara.m@gmail.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1209041738200.2754@ionos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-11-12 20:07:18 +01:00
David S. Miller d4185bbf62 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts:
	drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c

Minor conflict between the BCM_CNIC define removal in net-next
and a bug fix added to net.  Based upon a conflict resolution
patch posted by Stephen Rothwell.

Signed-off-by: David S. Miller <davem@davemloft.net>
2012-11-10 18:32:51 -05:00
Tejun Heo ef9fe980c6 cgroup_freezer: implement proper hierarchy support
Up until now, cgroup_freezer didn't implement hierarchy properly.
cgroups could be arranged in hierarchy but it didn't make any
difference in how each cgroup_freezer behaved.  They all operated
separately.

This patch implements proper hierarchy support.  If a cgroup is
frozen, all its descendants are frozen.  A cgroup is thawed iff it and
all its ancestors are THAWED.  freezer.self_freezing shows the current
freezing state for the cgroup itself.  freezer.parent_freezing shows
whether the cgroup is freezing because any of its ancestors is
freezing.

freezer_post_create() locks the parent and new cgroup and inherits the
parent's state and freezer_change_state() applies new state top-down
using cgroup_for_each_descendant_pre() which guarantees that no child
can escape its parent's state.  update_if_frozen() uses
cgroup_for_each_descendant_post() to propagate frozen states
bottom-up.

Synchronization could be coarser and easier by using a single mutex to
protect all hierarchy operations.  Finer grained approach was used
because it wasn't too difficult for cgroup_freezer and I think it's
beneficial to have an example implementation and cgroup_freezer is
rather simple and can serve a good one.

As this makes cgroup_freezer properly hierarchical,
freezer_subsys.broken_hierarchy marking is removed.

Note that this patch changes userland visible behavior - freezing a
cgroup now freezes all its descendants too.  This behavior change is
intended and has been warned via .broken_hierarchy.

v2: Michal spotted a bug in freezer_change_state() - descendants were
    inheriting from the wrong ancestor.  Fixed.

v3: Documentation/cgroups/freezer-subsystem.txt updated.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
2012-11-09 10:52:30 -08:00
Tejun Heo 5300a9b348 cgroup_freezer: add ->post_create() and ->pre_destroy() and track online state
A cgroup is online and visible to iteration between ->post_create()
and ->pre_destroy().  This patch introduces CGROUP_FREEZER_ONLINE and
toggles it from the newly added freezer_post_create() and
freezer_pre_destroy() while holding freezer->lock such that a
cgroup_freezer can be reilably distinguished to be online.  This will
be used by full hierarchy support.

ONLINE test is added to freezer_apply_state() but it currently doesn't
make any difference as freezer_write() can only be called for an
online cgroup.

Adjusting system_freezing_cnt on destruction is moved from
freezer_destroy() to the new freezer_pre_destroy() for consistency.

This patch doesn't introduce any noticeable behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
2012-11-09 09:12:30 -08:00
Tejun Heo a225218060 cgroup_freezer: introduce CGROUP_FREEZING_[SELF|PARENT]
Introduce FREEZING_SELF and FREEZING_PARENT and make FREEZING OR of
the two flags.  This is to prepare for full hierarchy support.

freezer_apply_date() is updated such that it can handle setting and
clearing of both flags.  The two flags are also exposed to userland
via read-only files self_freezing and parent_freezing.

Other than the added cgroupfs files, this patch doesn't introduce any
behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
2012-11-09 09:12:30 -08:00
Tejun Heo d6a2fe1342 cgroup_freezer: make freezer->state mask of flags
freezer->state was an enum value - one of THAWED, FREEZING and FROZEN.
As the scheduled full hierarchy support requires more than one
freezing condition, switch it to mask of flags.  If FREEZING is not
set, it's thawed.  FREEZING is set if freezing or frozen.  If frozen,
both FREEZING and FROZEN are set.  Now that tasks can be attached to
an already frozen cgroup, this also makes freezing condition checks
more natural.

This patch doesn't introduce any behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
2012-11-09 09:12:30 -08:00
Tejun Heo 04a4ec3257 cgroup_freezer: prepare freezer_change_state() for full hierarchy support
* Make freezer_change_state() take bool @freeze instead of enum
  freezer_state.

* Separate out freezer_apply_state() out of freezer_change_state().
  This makes freezer_change_state() a rather silly thin wrapper.  It
  will be filled with hierarchy handling later on.

This patch doesn't introduce any behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
2012-11-09 09:12:30 -08:00
Tejun Heo bcd66c894a cgroup_freezer: trivial cleanups
* Clean-up indentation and line-breaks.  Drop the invalid comment
  about freezer->lock.

* Make all internal functions take @freezer instead of both @cgroup
  and @freezer.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
2012-11-09 09:12:29 -08:00
Tejun Heo 574bd9f7c7 cgroup: implement generic child / descendant walk macros
Currently, cgroup doesn't provide any generic helper for walking a
given cgroup's children or descendants.  This patch adds the following
three macros.

* cgroup_for_each_child() - walk immediate children of a cgroup.

* cgroup_for_each_descendant_pre() - visit all descendants of a cgroup
  in pre-order tree traversal.

* cgroup_for_each_descendant_post() - visit all descendants of a
  cgroup in post-order tree traversal.

All three only require the user to hold RCU read lock during
traversal.  Verifying that each iterated cgroup is online is the
responsibility of the user.  When used with proper synchronization,
cgroup_for_each_descendant_pre() can be used to propagate state
updates to descendants in reliable way.  See comments for details.

v2: s/config/state/ in commit message and comments per Michal.  More
    documentation on synchronization rules.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujisu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-09 09:12:29 -08:00
Tejun Heo eb6fd5040e cgroup: use rculist ops for cgroup->children
Use RCU safe list operations for cgroup->children.  This will be used
to implement cgroup children / descendant walking which can be used by
controllers.

Note that cgroup_create() now puts a new cgroup at the end of the
->children list instead of head.  This isn't strictly necessary but is
done so that the iteration order is more conventional.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-09 09:12:29 -08:00
Tejun Heo a8638030f6 cgroup: add cgroup_subsys->post_create()
Currently, there's no way for a controller to find out whether a new
cgroup finished all ->create() allocatinos successfully and is
considered "live" by cgroup.

This becomes a problem later when we add generic descendants walking
to cgroup which can be used by controllers as controllers don't have a
synchronization point where it can synchronize against new cgroups
appearing in such walks.

This patch adds ->post_create().  It's called after all ->create()
succeeded and the cgroup is linked into the generic cgroup hierarchy.
This plays the counterpart of ->pre_destroy().

When used in combination with the to-be-added generic descendant
iterators, ->post_create() can be used to implement reliable state
inheritance.  It will be explained with the descendant iterators.

v2: Added a paragraph about its future use w/ descendant iterators per
    Michal.

v3: Forgot to add ->post_create() invocation to cgroup_load_subsys().
    Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Glauber Costa <glommer@parallels.com>
2012-11-09 09:12:29 -08:00
Paul E. McKenney 7bd8f2a74b rcu: Add tracing for synchronize_sched_expedited()
This commit adds a per-RCU-flavor "rcuexp" file that dumps out
statistics for synchonize_sched_expedited().

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:57:07 -08:00
Michael Wang 6ee0886ff6 rcu: Remove old debugfs interfaces and also RCU flavor name
This commit removes the old debugfs interfaces, so that the new
directory-per-RCU-flavor versions remain.  Because the RCU flavor is
given by the directory name, there is no need to print it out, so remove
the name from the printout.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:56:44 -08:00
Michael Wang a608d84bdb rcu: split 'rcuhier' to each flavor
This patch add new 'rcuhier' to each flavor's folder, now we could use:
	'cat /debugfs/rcu/rsp/rcuhier'
to get the selected rsp info.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:55:45 -08:00
Michael Wang 66b38bc52b rcu: split 'rcugp' to each flavor
This patch add new 'rcugp' to each flavor's folder, now we could use:
	'cat /debugfs/rcu/rsp/rcugp'
to get the selected rsp info.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:55:44 -08:00
Michael Wang 29c67764f1 rcu: split 'rcuboost' to each flavor
This patch add new 'rcuboost' to each flavor's folder, now we could use:
	'cat /debugfs/rcu/rsp/rcuboost'
to get the selected rsp info.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:55:42 -08:00
Michael Wang c25e557f5d rcu: split 'rcubarrier' to each flavor
This patch add new 'rcubarrier' to each flavor's folder, now we could use:
	'cat /debugfs/rcu/rsp/rcubarrier'
to get the selected rsp info.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:55:41 -08:00
Paul E. McKenney 42c3533eee rcu: Fix tracing formatting
The rcu_state structure's ->completed field is unsigned long, so this
commit adjusts show_one_rcugp()'s printf() format to suit.  Also add
the required ACCESS_ONCE() directives while we are in this function.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:55:30 -08:00
Michael Wang 5f4ee1fa16 rcu: Remove the interface "rcudata.csv"
This patch removes the interface "rcudata.csv" since it is apparently
not used.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:19 -08:00
Michael Wang c011c41f11 rcu: Replace the old interface with the new one
This patch removed the old RCU debugfs interface and replaced it with
the new one.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:18 -08:00
Michael Wang 51d0f16d49 rcu: Optimize the 'rcu_pending' for RCU trace
This patch implements the new 'rcu_pending' interface under each rsp
directory, by using the 'CPU units sequence reading', thus avoiding loss
of tracing data.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:17 -08:00
Michael Wang d29200efa2 rcu: Optimize the 'rcudata.csv' for RCU trace
This patch implements the new 'rcudata.csv' interface under each rsp
directory, by using the 'CPU units sequence reading', thus avoiding loss
of tracing data.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:16 -08:00
Michael Wang 878eda72e2 rcu: Optimize the 'rcudata' for RCU trace
This patch implements the new 'rcudata' interface under each rsp
directory, by using the 'CPU units sequence reading', thus avoiding loss
of tracing data.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:16 -08:00
Michael Wang 374b928ee8 rcu: Fundamental facility for 'CPU units sequence reading'
This patch add the fundamental facility used by the following patches, so we
can implement the 'CPU units sequence reading' later.

This helps us avoid losing data when there are too many CPUs and too
small of a buffer, since this new approach allows userspace to read out
the data one CPU at a time.  Thus, if the buffer is not large enough,
userspace will get whatever CPUs fit, and can then issue another read
for the remainder of the data.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:15 -08:00
Michael Wang 573bcd40d2 rcu: Create directory for each flavor of rcu
This patch will create subdirectory according to each flavor of rcu, the new
structure will be:

	/debugfs/rcu/ -> rsp_0
		      -> rsp_1
		      -> ...

So we can go to '/debugfs/rcu/rsp_0' and get the cpu info of rsp_0 there.
The flavors of RCU are currently rcu_bh, rcu_preempt, and rcu_sched.

Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:14 -08:00
Paul E. McKenney a30489c522 rcu: Instrument synchronize_rcu_expedited() for debugfs tracing
This commit adds the counters to rcu_state and updates them in
synchronize_rcu_expedited() to provide the data needed for debugfs
tracing.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:13 -08:00
Paul E. McKenney 40694d6644 rcu: Move synchronize_sched_expedited() state to rcu_state
Tracing (debugfs) of expedited RCU primitives is required, which in turn
requires that the relevant data be located where the tracing code can find
it, not in its current static global variables in kernel/rcutree.c.
This commit therefore moves sync_sched_expedited_started and
sync_sched_expedited_done to the rcu_state structure, as fields
->expedited_start and ->expedited_done, respectively.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:12 -08:00
Paul E. McKenney 1924bcb025 rcu: Avoid counter wrap in synchronize_sched_expedited()
There is a counter scheme similar to ticket locking that
synchronize_sched_expedited() uses to service multiple concurrent
callers with the same expedited grace period.  Upon entry, a
sync_sched_expedited_started variable is atomically incremented,
and upon completion of a expedited grace period a separate
sync_sched_expedited_done variable is atomically incremented.

However, if a synchronize_sched_expedited() is delayed while
in try_stop_cpus(), concurrent invocations will increment the
sync_sched_expedited_started counter, which will eventually overflow.
If the original synchronize_sched_expedited() resumes execution just
as the counter overflows, a concurrent invocation could incorrectly
conclude that an expedited grace period elapsed in zero time, which
would be bad.  One could rely on counter size to prevent this from
happening in practice, but the goal is to formally validate this
code, so it needs to be fixed anyway.

This commit therefore checks the gap between the two counters before
incrementing sync_sched_expedited_started, and if the gap is too
large, does a normal grace period instead.  Overflow is thus only
possible if there are more than about 3.5 billion threads on 32-bit
systems, which can be excluded until such time as task_struct fits
into a single byte and 4G/4G patches are accepted into mainline.
It is also easy to encode this limitation into mechanical theorem
provers.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:12 -08:00
Paul E. McKenney 7b2e6011f1 rcu: Rename ->onofflock to ->orphan_lock
The ->onofflock field in the rcu_state structure at one time synchronized
CPU-hotplug operations for RCU.  However, its scope has decreased over time
so that it now only protects the lists of orphaned RCU callbacks.  This
commit therefore renames it to ->orphan_lock to reflect its current use.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08 11:50:11 -08:00
Tao Ma 316eb661f1 cgroup: set 'start' with the right value in cgroup_path.
'start' is set to buf + buflen and do the '--' immediately.
Just set it to 'buf + buflen - 1' directly.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
2012-11-08 06:23:02 -08:00
Tejun Heo 5b805f2a76 Merge branch 'cgroup/for-3.7-fixes' into cgroup/for-3.8
This is to receive device_cgroup fixes so that further device_cgroup
changes can be made in cgroup/for-3.8.

Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-06 12:26:23 -08:00
Tejun Heo 1db1e31b1e Merge branch 'cgroup-rmdir-updates' into cgroup/for-3.8
Pull rmdir updates into for-3.8 so that further callback updates can
be put on top.  This pull created a trivial conflict between the
following two commits.

  8c7f6edbda ("cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested for them")
  ed95779340 ("cgroup: kill cgroup_subsys->__DEPRECATED_clear_css_refs")

The former added a field to cgroup_subsys and the latter removed one
from it.  They happen to be colocated causing the conflict.  Keeping
what's added and removing what's removed resolves the conflict.

Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-05 09:21:51 -08:00