Oleg Nesterov d80e731eca epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree() ... This patch is intentionally incomplete to simplify the review. It ignores ep_unregister_pollwait() which plays with the same wqh. See the next change. epoll assumes that the EPOLL_CTL_ADD'ed file controls everything f_op->poll() needs. In particular it assumes that the wait queue can't go away until eventpoll_release(). This is not true in case of signalfd, the task which does EPOLL_CTL_ADD uses its ->sighand which is not connected to the file. This patch adds the special event, POLLFREE, currently only for epoll. It expects that init_poll_funcptr()'ed hook should do the necessary cleanup. Perhaps it should be defined as EPOLLFREE in eventpoll. __cleanup_sighand() is changed to do wake_up_poll(POLLFREE) if ->signalfd_wqh is not empty, we add the new signalfd_cleanup() helper. ep_poll_callback(POLLFREE) simply does list_del_init(task_list). This make this poll entry inconsistent, but we don't care. If you share epoll fd which contains our sigfd with another process you should blame yourself. signalfd is "really special". I simply do not know how we can define the "right" semantics if it used with epoll. The main problem is, epoll calls signalfd_poll() once to establish the connection with the wait queue, after that signalfd_poll(NULL) returns the different/inconsistent results depending on who does EPOLL_CTL_MOD/signalfd_read/etc. IOW: apart from sigmask, signalfd has nothing to do with the file, it works with the current thread. In short: this patch is the hack which tries to fix the symptoms. It also assumes that nobody can take tasklist_lock under epoll locks, this seems to be true. Note: - we do not have wake_up_all_poll() but wake_up_poll() is fine, poll/epoll doesn't use WQ_FLAG_EXCLUSIVE. - signalfd_cleanup() uses POLLHUP along with POLLFREE, we need a couple of simple changes in eventpoll.c to make sure it can't be "lost". Reported-by: Maxime Bizon <mbizon@freebox.fr> Cc: <stable@kernel.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2012-02-24 11:42:50 -08:00
..
debug	module: struct module_ref should contains long fields	2012-01-13 09:32:14 +10:30
events	perf: Fix double start/stop in x86_pmu_start()	2012-02-07 16:58:56 +01:00
gcov	…
irq	module_param: make bool parameters really bool (core code)	2012-01-13 09:32:18 +10:30
power	PM / Freezer: Thaw only kernel threads if freezing of kernel threads fails	2012-02-04 22:23:05 +01:00
sched	sched/rt: Fix task stack corruption under __ARCH_WANT_INTERRUPTS_ON_CTXSW	2012-01-27 12:49:41 +01:00
time	Merge branch 'rcu/fixes-for-v3.2' into rcu/urgent	2012-01-16 09:41:18 -08:00
trace	Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2012-01-15 11:26:35 -08:00
.gitignore	…
Kconfig.freezer	…
Kconfig.hz	…
Kconfig.locks	…
Kconfig.preempt	…
Makefile	PM: Make sysrq-o be available for CONFIG_PM unset	2012-01-14 00:33:03 +01:00
acct.c	Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2012-01-08 12:19:57 -08:00
async.c	kernel/async: remove redundant declaration.	2012-01-13 09:32:18 +10:30
audit.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit	2012-01-17 16:41:31 -08:00
audit.h	audit: remove AUDIT_SETUP_CONTEXT as it isn't used	2012-01-17 16:16:57 -05:00
audit_tree.c	…
audit_watch.c	…
auditfilter.c	audit: allow interfield comparison in audit rules	2012-01-17 16:17:01 -05:00
auditsc.c	kernel-doc: fix new warnings in auditsc.c	2012-01-23 08:44:53 -08:00
backtracetest.c	…
bounds.c	…
capability.c	Revert "capabitlies: ns_capable can use the cap helpers rather than lsm call"	2012-01-17 10:19:41 -08:00
cgroup.c	Merge branch 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2012-01-09 12:59:24 -08:00
cgroup_freezer.c	Merge branch 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2012-01-09 12:59:24 -08:00
compat.c	kernel: Fix files explicitly needing EXPORT_SYMBOL infrastructure	2011-10-31 19:30:05 -04:00
configs.c	…
cpu.c	Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm	2012-01-08 13:10:57 -08:00
cpu_pm.c	cpu_pm: call notifiers during suspend	2011-09-23 12:05:29 +05:30
cpuset.c	Merge branch 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2012-01-09 12:59:24 -08:00
crash_dump.c	Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux	2011-11-06 19:44:47 -08:00
cred.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
delayacct.c	…
dma.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
elfcore.c	…
exec_domain.c	…
exit.c	sched: Fix ancient race in do_exit()	2012-01-27 11:55:36 +01:00
extable.c	…
fork.c	epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree()	2012-02-24 11:42:50 -08:00
freezer.c	freezer: kill unused set_freezable_with_signal()	2011-11-23 09:28:17 -08:00
futex.c	futex: Fix uninterruptible loop due to gate_area	2011-12-31 11:48:28 -08:00
futex_compat.c	…
groups.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
hrtimer.c	Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2011-11-28 08:43:52 -08:00
hung_task.c	hung_task: fix false positive during vfork	2012-01-03 16:14:32 -08:00
irq_work.c	kernel: fix two implicit header assumptions in irq_work.c	2011-10-31 09:20:12 -04:00
itimer.c	[S390] cputime: add sparse checking and cleanup	2011-12-15 14:56:19 +01:00
jump_label.c	Merge remote-tracking branch 'tip/perf/core' into kvm-updates/3.3	2011-12-27 11:22:24 +02:00
kallsyms.c	…
kexec.c	kdump: crashk_res init check for /sys/kernel/kexec_crash_size	2012-01-12 20:13:11 -08:00
kfifo.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
kmod.c	Merge branch 'pm-sleep' into pm-for-linus	2011-12-25 23:42:20 +01:00
kprobes.c	kprobes: fix a memory leak in function pre_handler_kretprobe()	2012-02-03 16:16:41 -08:00
ksysfs.c	kernel: ksysfs.c is implicitly using stat.h	2011-10-31 09:20:13 -04:00
kthread.c	freezer: kill unused set_freezable_with_signal()	2011-11-23 09:28:17 -08:00
latencytop.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
lockdep.c	Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2012-01-06 08:02:58 -08:00
lockdep_internals.h	…
lockdep_proc.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
lockdep_states.h	…
module.c	error: implicit declaration of function 'module_flags_taint'	2012-01-15 16:21:07 -08:00
mutex-debug.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
mutex-debug.h	…
mutex.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
mutex.h	…
notifier.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
nsproxy.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
padata.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
panic.c	panic: don't print redundant backtraces on oops	2012-01-12 20:13:11 -08:00
params.c	module: make module param bint handle nul value	2012-02-14 11:02:15 +10:30
pid.c	vfs: fix panic in __d_lookup() with high dentry hashtable counts	2012-02-13 20:45:38 -05:00
pid_namespace.c	sysctl: add the kernel.ns_last_pid control	2012-01-12 20:13:11 -08:00
posix-cpu-timers.c	[S390] cputime: add sparse checking and cleanup	2011-12-15 14:56:19 +01:00
posix-timers.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
printk.c	module_param: make bool parameters really bool (core code)	2012-01-13 09:32:18 +10:30
profile.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
ptrace.c	Merge branch 'for-linus' of git://selinuxproject.org/~jmorris/linux-security	2012-01-14 18:36:33 -08:00
range.c	range: fix bogus misuse of module.h to get printk()	2011-10-31 09:20:11 -04:00
rcu.h	rcu: Deconfuse dynticks entry-exit tracing	2011-12-11 10:31:42 -08:00
rcupdate.c	rcu: Detect illegal rcu dereference in extended quiescent state	2011-12-11 10:31:30 -08:00
rcutiny.c	rcu: Augment rcu_batch_end tracing for idle and callback state	2011-12-11 10:32:22 -08:00
rcutiny_plugin.h	rcu: Apply ACCESS_ONCE() to rcu_boost() return value	2011-12-11 10:33:19 -08:00
rcutorture.c	rcu: Add missing __cpuinit annotation in rcutorture code	2012-01-16 09:44:05 -08:00
rcutree.c	rcu: Augment rcu_batch_end tracing for idle and callback state	2011-12-11 10:32:22 -08:00
rcutree.h	rcu: Keep invoking callbacks if CPU otherwise idle	2011-12-11 10:32:09 -08:00
rcutree_plugin.h	rcu: Apply ACCESS_ONCE() to rcu_boost() return value	2011-12-11 10:33:19 -08:00
rcutree_trace.c	rcu: Track idleness independent of idle tasks	2011-12-11 10:31:24 -08:00
relay.c	relay: prevent integer overflow in relay_open()	2012-02-10 09:04:49 +01:00
res_counter.c	net: introduce res_counter_charge_nofail() for socket allocations	2012-01-22 15:08:46 -05:00
resource.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
rtmutex-debug.c	lockdep, rtmutex, bug: Show taint flags on error	2011-12-06 08:16:49 +01:00
rtmutex-debug.h	…
rtmutex-tester.c	rtmutex-tester: convert sysdev_class to a regular subsystem	2011-12-14 14:54:22 -08:00
rtmutex.c	Revert "rcu: Permit rt_mutex_unlock() with irqs disabled"	2011-12-11 10:33:18 -08:00
rtmutex.h	…
rtmutex_common.h	…
rwsem.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
seccomp.c	seccomp: audit abnormal end to a process due to seccomp	2012-01-17 16:16:55 -05:00
semaphore.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
signal.c	user namespace: make signal.c respect user namespaces	2012-01-10 16:30:54 -08:00
smp.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
softirq.c	rcu: Fix early call to rcu_idle_enter()	2011-12-11 10:31:38 -08:00
spinlock.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
srcu.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
stacktrace.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
stop_machine.c	Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux	2011-11-06 19:44:47 -08:00
sys.c	c/r: prctl: add PR_SET_MM codes to set up mm_struct entries	2012-01-12 20:13:13 -08:00
sys_ni.c	Cross Memory Attach	2011-10-31 17:30:44 -07:00
sysctl.c	x86: Panic on detection of stack overflow	2011-12-05 11:37:47 +01:00
sysctl_binary.c	binary_sysctl(): fix memory leak	2011-12-20 10:25:04 -08:00
sysctl_check.c	…
taskstats.c	…
test_kprobes.c	…
time.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
timeconst.pl	…
timer.c	Merge branch 'core-debugobjects-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2012-01-06 07:53:34 -08:00
tracepoint.c	tracepoints/module: Fix disabling tracepoints with taint CRAP or OOT	2012-01-16 11:35:57 -05:00
tsacct.c	[S390] cputime: add sparse checking and cleanup	2011-12-15 14:56:19 +01:00
uid16.c	…
up.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
user-return-notifier.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
user.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
user_namespace.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
utsname.c	kernel: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
utsname_sysctl.c	Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux	2011-11-06 19:44:47 -08:00
wait.c	lockdep/waitqueues: Add better annotation	2011-12-21 10:07:39 +01:00
watchdog.c	bugs, x86: Fix printk levels for panic, softlockups and stack dumps	2012-01-26 21:28:45 +01:00
workqueue.c	workqueue: make alloc_workqueue() take printf fmt and args for name	2012-01-10 16:30:54 -08:00
workqueue_sched.h	…