kernel/trace/ring_buffer.c: In function 'rb_tail_page_update':
kernel/trace/ring_buffer.c:849: warning: value computed is not used
kernel/trace/ring_buffer.c:850: warning: value computed is not used
Add "(void)"s to fix this warning, because we don't need here to handle
the fail case of cmpxchg, it's fine if an interrupt already did the
job.
Changed from V1:
Add a comment(which is written by Steven) for it.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
The stat entries can be freed when the stat file is being read.
The worse is, the ptr can be freed immediately after it's returned
from workqueue_stat_start/next().
Add a refcnt to struct cpu_workqueue_stats to avoid use-after-free.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A51B16F.6010608@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add stat_release() callback to struct tracer_stat, so a stat tracer
can release it's entries after the stat file has been read out.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A51B16A.6020708@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
So we have:
- kmemtrace_print_alloc/free() for kmemtrace default output
- kmemtrace_print_alloc/free_user() for binary output used
by kmemtrace-user.
Suggested-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A51B288.70505@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Remove the obsolete seq_print_ip_sym() usage and replace it
by the %pf format in order to print function symbols.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
LKML-Reference: <1247107590-6428-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Remove the obsolete seq_print_ip_sym() usage and replace it
by the %pf format in order to print function symbols.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <1247107590-6428-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Remove empty subsystem and its directory when module unload.
Before patch:
# rmmod trace-events-sample.ko
# ls sample
enable filter
After patch:
# rmmod trace-events-sample.ko
# ls sample
ls: cannot access sample: No such file or directory
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: Tom Zanussi <tzanussi@gmail.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A55A8BE.9010707@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
No need to save preds to event_subsystem, because it's not used.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: Tom Zanussi <tzanussi@gmail.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A55A83C.1030005@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch converts the ring buffers into a completely lockless
buffer recording system. The read side still takes locks since
we still serialize readers. But the writers are the ones that
must be lockless (those can happen in NMIs).
The main change is to the "head_page" pointer. We write to the
tail, and read from the head. The "head_page" pointer in the cpu
buffer is now just a reference to where to look. The real head
page is now kept in the head_page->list->prev->next pointer.
That is, in the list head of the previous page we set flags.
The list pages are allocated to be aligned such that the lowest
significant bits are always zero pointing to the list. This gives
us play to put in flags to their pointers.
bit 0: set when the page is a head page
bit 1: set when the writer is moving the page (for overwrite mode)
cmpxchg is used to update the pointer.
When the writer wraps the buffer and the tail meets the head,
in overwrite mode, the writer must move the head page forward.
It first uses cmpxchg to change the pointer flag from 1 to 2.
Once this is done, the reader on another CPU will not take the
page from the buffer.
The writers need to protect against interrupts (we don't bother with
disabling interrupts because NMIs are allowed to write too).
After the writer sets the pointer flag to 2, it takes care to
manage interrupts coming in. This is discribed in detail within the
comments of the code.
Changes in version 2:
- Let reader reset entries value of header page.
- Fix tail page passing commit page on reader page test.
- Always increment entries and write counter in rb_tail_page_update
- Add safety check in rb_set_commit_to_write to break out of infinite loop
- add mask in rb_is_reader_page
[ Impact: lock free writing to the ring buffer ]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This patch changes the ring buffer data pages from using a link list
head pointer, to making each buffer page point to another buffer page
and never back to a "head".
This makes the handling of the ring buffer less complex, since the
traversing of the ring buffer pages no longer needs to account for the
head pointer.
This change also is needed to make the ring buffer lockless.
[
Changes in version 2:
- Added change that Lai Jiangshan mentioned.
From: Lai Jiangshan <laijs@cn.fujitsu.com>
Date: Thu, 11 Jun 2009 11:25:48 +0800
LKML-Reference: <4A30793C.6090208@cn.fujitsu.com>
I'm not sure whether these 4 lines:
bpage = list_entry(pages.next, struct buffer_page, list);
list_del_init(&bpage->list);
cpu_buffer->pages = &bpage->list;
list_splice(&pages, cpu_buffer->pages);
equal to these 2 lines:
cpu_buffer->pages = pages.next;
list_del(&pages);
If there are equivalent, I think the second one
are simpler. It may be not a really necessarily cleanup.
What I asked is: if there are equivalent, could you use these two line:
cpu_buffer->pages = pages.next;
list_del(&pages);
]
[ Impact: simplify the ring buffer to help make it lockless ]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Currently by default the output of kmemtrace is binary format instead
of human-readable output.
This patch makes the following changes:
- We'll see human-readable output by default
- We'll see binary output if 'bin' option is set
Note: you may probably need to explicitly disable context-info binary
output:
# echo 0 > options/context-info
# echo 1 > options/bin
# cat trace_pipe
v2:
- use %pF to print call_site
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A4DD0A0.5060500@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We already have ftrace= boot option, and this adds a similar
boot option for trace events, so allow trace events to be
enabled at boot, for boot debugging purpose.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A4ACE29.3010407@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use struct list instead of struct hlist for managing
insn_pages, because insn_pages doesn't use hash table.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20090630210814.17851.64651.stgit@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Remove needless kprobe_insn_mutex unlocking during safety check
in garbage collection, because if someone releases a dirty slot
during safety check (which ensures other cpus doesn't execute
all dirty slots), the safety check must be fail. So, we need to
hold the mutex while checking safety.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20090630210809.17851.28781.stgit@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
To use boot tracer, one should pass initcall_debug as well as
ftrace=initcall to the command line.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A48735E.9050002@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Some fields for struct ftrace_graph_ret are missed
when they are exported to user.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A448FB6.5000302@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This made my machine completely frozen:
# echo 1 > /proc/sys/kernel/stack_tracer_enabled
# echo 2 > /proc/sys/kernel/stack_tracer_enabled
The cause is register_ftrace_function() was called twice.
Also fix ftrace_enabled sysctl, though seems nothing bad happened
as I tested it.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A448D17.9010305@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The first entry of the ftrace profile was always skipped when
reading trace_stat/functionX.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A443D59.4080307@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In hunting down the cause for the hwlat_detector ring buffer spew in
my failed -next builds it became obvious that folks are now treating
ring_buffer as something that is generic independent of tracing and thus,
suitable for public driver consumption.
Given that there are only a few minor areas in ring_buffer that have any
reliance on CONFIG_TRACING or CONFIG_FUNCTION_TRACER, provide stubs for
those and make it generally available.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Cc: Jon Masters <jcm@jonmasters.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090625053012.GB19944@linux-sh.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We should be able to specify [KMG] when setting trace_buf_size
boot option, as documented in kernel-parameters.txt
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A41F2DB.4020102@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When the output of set_ftrace_filter is larger than PAGE_SIZE,
t_hash_start() will be called the 2nd time, and then we start
from the head of a hlist, which is wrong and causes some entries
to be outputed twice.
The worse is, if the hlist is large enough, reading set_ftrace_filter
won't stop but in a dead loop.
Reviewed-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A41876E.2060407@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It's rather confusing that in t_start(), in some cases @pos is
incremented, and in some cases it's decremented and then incremented.
This patch rewrites t_start() in a much more general way.
Thus we fix a bug that if ftrace_filtered == 1, functions have tracer
hooks won't be printed, because the branch is always unreachable:
static void *t_start(...)
{
...
if (!p)
return t_hash_start(m, pos);
return p;
}
Before:
# echo 'sys_open' > /mnt/tracing/set_ftrace_filter
# echo 'sys_write:traceon:4' >> /mnt/tracing/set_ftrace_filter
sys_open
After:
# echo 'sys_open' > /mnt/tracing/set_ftrace_filter
# echo 'sys_write:traceon:4' >> /mnt/tracing/set_ftrace_filter
sys_open
sys_write:traceon:count=4
Reviewed-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A41874B.4090507@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It's wrong to increment @pos in g_start(). It causes some entries
lost when reading set_graph_function, if the output of the file
is larger than PAGE_SIZE.
Reviewed-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A418738.7090401@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The iterator is m->private, but it's not reset to trace_types in
t_start(). If the output is larger than PAGE_SIZE and t_start()
is called the 2nd time, things will go wrong.
Reviewed-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A418728.5020506@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It's wrong to increment @pos in stat_seq_start(). It causes some
stat entries lost when reading stat file, if the output of the file
is larger than PAGE_SIZE.
Reviewed-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A418716.90209@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It's wrong to increment @pos in t_start(), otherwise we'll lose
some entries when reading printk_formats, if the output is larger
than PAGE_SIZE.
Reported-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Reviewed-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A4186FA.1020106@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
While testing syscall tracepoints posted by Jason, I found 3 entries
were missing when reading available_events. The output size of
available_events is < 4 pages, which means we lost 1 entry per page.
The cause is, it's wrong to increment @pos in s_start().
Actually there's another bug here -- reading avaiable_events/set_events
can race with module unload:
# cat available_events |
s_start() |
s_stop() |
| # rmmod foo.ko
s_start() |
call = list_entry(m->private) |
@call might be freed and accessing it will lead to crash.
Reviewed-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A4186DD.6090405@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
SLAB uses get/put_online_cpus() which use a mutex which is itself only
initialized when cpu_hotplug_init() is called. Currently we hang suring
boot in SLAB due to doing that too late.
Reported by James Bottomley and Sachin Sant (and possibly others).
Debugged by Benjamin Herrenschmidt.
This just removes the dynamic initialization of the data structures, and
replaces it with a static one, avoiding this dependency entirely, and
removing one unnecessary special initcall.
Tested-by: Sachin Sant <sachinp@in.ibm.com>
Tested-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
genirq, irq.h: Fix kernel-doc warnings
genirq: fix comment to say IRQ_WAKE_THREAD
* 'perfcounters-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (49 commits)
perfcounter: Handle some IO return values
perf_counter: Push perf_sample_data through the swcounter code
perf_counter tools: Define and use our own u64, s64 etc. definitions
perf_counter: Close race in perf_lock_task_context()
perf_counter, x86: Improve interactions with fast-gup
perf_counter: Simplify and fix task migration counting
perf_counter tools: Add a data file header
perf_counter: Update userspace callchain sampling uses
perf_counter: Make callchain samples extensible
perf report: Filter to parent set by default
perf_counter tools: Handle lost events
perf_counter: Add event overlow handling
fs: Provide empty .set_page_dirty() aop for anon inodes
perf_counter: tools: Makefile tweaks for 64-bit powerpc
perf_counter: powerpc: Add processor back-end for MPC7450 family
perf_counter: powerpc: Make powerpc perf_counter code safe for 32-bit kernels
perf_counter: powerpc: Change how processor-specific back-ends get selected
perf_counter: powerpc: Use unsigned long for register and constraint values
perf_counter: powerpc: Enable use of software counters on 32-bit powerpc
perf_counter tools: Add and use isprint()
...
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Fix out of scope variable access in sched_slice()
sched: Hide runqueues from direct refer at source code level
sched: Remove unneeded __ref tag
sched, x86: Fix cpufreq + sched_clock() TSC scaling
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (24 commits)
tracing/urgent: warn in case of ftrace_start_up inbalance
tracing/urgent: fix unbalanced ftrace_start_up
function-graph: add stack frame test
function-graph: disable when both x86_32 and optimize for size are configured
ring-buffer: have benchmark test print to trace buffer
ring-buffer: do not grab locks in nmi
ring-buffer: add locks around rb_per_cpu_empty
ring-buffer: check for less than two in size allocation
ring-buffer: remove useless compile check for buffer_page size
ring-buffer: remove useless warn on check
ring-buffer: use BUF_PAGE_HDR_SIZE in calculating index
tracing: update sample event documentation
tracing/filters: fix race between filter setting and module unload
tracing/filters: free filter_string in destroy_preds()
ring-buffer: use commit counters for commit pointer accounting
ring-buffer: remove unused variable
ring-buffer: have benchmark test handle discarded events
ring-buffer: prevent adding write in discarded area
tracing/filters: strloc should be unsigned short
tracing/filters: operand can be negative
...
Fix up kmemcheck-induced conflict in kernel/trace/ring_buffer.c manually
Push the perf_sample_data further outwards to the swcounter interface,
to abstract it away some more.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Prevent from further ftrace_start_up inbalances so that we avoid
future nop patching omissions with dynamic ftrace.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Perfcounter reports the following stats for a wide system
profiling:
#
# (2364 samples)
#
# Overhead Symbol
# ........ ......
#
15.40% [k] mwait_idle_with_hints
8.29% [k] read_hpet
5.75% [k] ftrace_caller
3.60% [k] ftrace_call
[...]
This snapshot has been taken while neither the function tracer nor
the function graph tracer was running.
With dynamic ftrace, such results show a wrong ftrace behaviour
because all calls to ftrace_caller or ftrace_graph_caller (the patched
calls to mcount) are supposed to be patched into nop if none of those
tracers are running.
The problem occurs after the first run of the function tracer. Once we
launch it a second time, the callsites will never be nopped back,
unless you set custom filters.
For example it happens during the self tests at boot time.
The function tracer selftest runs, and then the dynamic tracing is
tested too. After that, the callsites are left un-nopped.
This is because the reset callback of the function tracer tries to
unregister two ftrace callbacks in once: the common function tracer
and the function tracer with stack backtrace, regardless of which
one is currently in use.
It then creates an unbalance on ftrace_start_up value which is expected
to be zero when the last ftrace callback is unregistered. When it
reaches zero, the FTRACE_DISABLE_CALLS is set on the next ftrace
command, triggering the patching into nop. But since it becomes
unbalanced, ie becomes lower than zero, if the kernel functions
are patched again (as in every further function tracer runs), they
won't ever be nopped back.
Note that ftrace_call and ftrace_graph_call are still patched back
to ftrace_stub in the off case, but not the callers of ftrace_call
and ftrace_graph_caller. It means that the tracing is well deactivated
but we waste a useless call into every kernel function.
This patch just unregisters the right ftrace_ops for the function
tracer on its reset callback and ignores the other one which is
not registered, fixing the unbalance. The problem also happens
is .30
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: stable@kernel.org
The bug is ancient.
If we trace the sub-thread of our natural child and this sub-thread exits,
we update parent->signal->cxxx fields. But we should not do this until
the whole thread-group exits, otherwise we account this thread (and all
other live threads) twice.
Add the task_detached() check. No need to check thread_group_empty(),
wait_consider_task()->delay_group_leader() already did this.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Vitaly Mayatskikh <vmayatsk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
perf_lock_task_context() is buggy because it can return a dead
context.
the RCU read lock in perf_lock_task_context() only guarantees
the memory won't get freed, it doesn't guarantee the object is
valid (in our case refcount > 0).
Therefore we can return a locked object that can get freed the
moment we release the rcu read lock.
perf_pin_task_context() then increases the refcount and does an
unlock on freed memory.
That increased refcount will cause a double free, in case it
started out with 0.
Ammend this by including the get_ctx() functionality in
perf_lock_task_context() (all users already did this later
anyway), and return a NULL context when the found one is
already dead.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The task migrations counter was causing rare and hard to decypher
memory corruptions under load. After a day of debugging and bisection
we found that the problem was introduced with:
3f731ca: perf_counter: Fix cpu migration counter
Turning them off fixes the crashes. Incidentally, the whole
perf_counter_task_migration() logic can be done simpler as well,
by injecting a proper sw-counter event.
This cleanup also fixed the crashes. The precise failure mode is
not completely clear yet, but we are clearly not unhappy about
having a fix ;-)
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In case gcc does something funny with the stack frames, or the return
from function code, we would like to detect that.
An arch may implement passing of a variable that is unique to the
function and can be saved on entering a function and can be tested
when exiting the function. Usually the frame pointer can be used for
this purpose.
This patch also implements this for x86. Where it passes in the stack
frame of the parent function, and will test that frame on exit.
There was a case in x86_32 with optimize for size (-Os) where, for a
few functions, gcc would align the stack frame and place a copy of the
return address into it. The function graph tracer modified the copy and
not the actual return address. On return from the funtion, it did not go
to the tracer hook, but returned to the parent. This broke the function
graph tracer, because the return of the parent (where gcc did not do
this funky manipulation) returned to the location that the child function
was suppose to. This caused strange kernel crashes.
This test detected the problem and pointed out where the issue was.
This modifies the parameters of one of the functions that the arch
specific code calls, so it includes changes to arch code to accommodate
the new prototype.
Note, I notice that the parsic arch implements its own push_return_trace.
This is now a generic function and the ftrace_push_return_trace should be
used instead. This patch does not touch that code.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
On x86_32, when optimize for size is set, gcc may align the frame pointer
and make a copy of the the return address inside the stack frame.
The return address that is located in the stack frame may not be
the one used to return to the calling function. This will break the
function graph tracer.
The function graph tracer replaces the return address with a jump to a hook
function that can trace the exit of the function. If it only replaces
a copy, then the hook will not be called when the function returns.
Worse yet, when the parent function returns, the function graph tracer
will return back to the location of the child function which will
easily crash the kernel with weird results.
To see the problem, when i386 is compiled with -Os we get:
c106be03: 57 push %edi
c106be04: 8d 7c 24 08 lea 0x8(%esp),%edi
c106be08: 83 e4 e0 and $0xffffffe0,%esp
c106be0b: ff 77 fc pushl 0xfffffffc(%edi)
c106be0e: 55 push %ebp
c106be0f: 89 e5 mov %esp,%ebp
c106be11: 57 push %edi
c106be12: 56 push %esi
c106be13: 53 push %ebx
c106be14: 81 ec 8c 00 00 00 sub $0x8c,%esp
c106be1a: e8 f5 57 fb ff call c1021614 <mcount>
When it is compiled with -O2 instead we get:
c10896f0: 55 push %ebp
c10896f1: 89 e5 mov %esp,%ebp
c10896f3: 83 ec 28 sub $0x28,%esp
c10896f6: 89 5d f4 mov %ebx,0xfffffff4(%ebp)
c10896f9: 89 75 f8 mov %esi,0xfffffff8(%ebp)
c10896fc: 89 7d fc mov %edi,0xfffffffc(%ebp)
c10896ff: e8 d0 08 fa ff call c1029fd4 <mcount>
The compile with -Os will align the stack pointer then set up the
frame pointer (%ebp), and it copies the return address back into
the stack frame. The change to the return address in mcount is done
to the copy and not the real place holder of the return address.
Then compile with -O2 sets up the frame pointer first, this makes
the change to the return address by mcount affect where the function
will jump on exit.
Reported-by: Jake Edge <jake@lwn.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Enable gcov profiling of the entire kernel on x86_64. Required changes
include disabling profiling for:
* arch/kernel/acpi/realmode and arch/kernel/boot/compressed:
not linked to main kernel
* arch/vdso, arch/kernel/vsyscall_64 and arch/kernel/hpet:
profiling causes segfaults during boot (incompatible context)
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Enable the use of GCC's coverage testing tool gcov [1] with the Linux
kernel. gcov may be useful for:
* debugging (has this code been reached at all?)
* test improvement (how do I change my test to cover these lines?)
* minimizing kernel configurations (do I need this option if the
associated code is never run?)
The profiling patch incorporates the following changes:
* change kbuild to include profiling flags
* provide functions needed by profiling code
* present profiling data as files in debugfs
Note that on some architectures, enabling gcc's profiling option
"-fprofile-arcs" for the entire kernel may trigger compile/link/
run-time problems, some of which are caused by toolchain bugs and
others which require adjustment of architecture code.
For this reason profiling the entire kernel is initially restricted
to those architectures for which it is known to work without changes.
This restriction can be lifted once an architecture has been tested
and found compatible with gcc's profiling. Profiling of single files
or directories is still available on all platforms (see config help
text).
[1] http://gcc.gnu.org/onlinedocs/gcc/Gcov.html
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Call constructors (gcc-generated initcall-like functions) during kernel
start and module load. Constructors are e.g. used for gcov data
initialization.
Disable constructor support for usermode Linux to prevent conflicts with
host glibc.
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
clone_nsproxy() does useless copying of old nsproxy -- every pointer will
be rewritten to new ns or to old ns. Remove copying, rename
clone_nsproxy(), create_nsproxy() will be used by C/R code to create fresh
nsproxy on restart.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
create_uts_ns() will be used by C/R to create fresh uts_ns.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Lai Jiangshan
Ingo Molnar
Li Zefan
Frederic Weisbecker
Xiao Guangrong
Steven Rostedt
Masami Hiramatsu
Paul Mundt
Linus Torvalds
Peter Zijlstra
Oleg Nesterov
Peter Oberparleiter
Alexey Dobriyan