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
events	perf: Fix double start/stop in x86_pmu_start()	2012-02-07 16:58:56 +01:00
gcov
irq
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
trace
.gitignore
acct.c
async.c
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
cgroup.c
cgroup_freezer.c
compat.c
configs.c
cpu.c
cpu_pm.c
cpuset.c
crash_dump.c
cred.c
delayacct.c
dma.c
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
futex.c
futex_compat.c
groups.c
hrtimer.c
hung_task.c
irq_work.c
itimer.c
jump_label.c
kallsyms.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c
kfifo.c
kmod.c
kprobes.c	kprobes: fix a memory leak in function pre_handler_kretprobe()	2012-02-03 16:16:41 -08:00
ksysfs.c
kthread.c
latencytop.c
lockdep.c
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
Makefile
module.c
mutex-debug.c
mutex-debug.h
mutex.c
mutex.h
notifier.c
nsproxy.c
padata.c
panic.c
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
posix-cpu-timers.c
posix-timers.c
printk.c
profile.c
ptrace.c
range.c
rcu.h
rcupdate.c
rcutiny.c
rcutiny_plugin.h
rcutorture.c
rcutree.c
rcutree.h
rcutree_plugin.h
rcutree_trace.c
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
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c
rtmutex.h
rtmutex_common.h
rwsem.c
seccomp.c	seccomp: audit abnormal end to a process due to seccomp	2012-01-17 16:16:55 -05:00
semaphore.c
signal.c
smp.c
softirq.c
spinlock.c
srcu.c
stacktrace.c
stop_machine.c
sys.c
sys_ni.c
sysctl.c
sysctl_binary.c
sysctl_check.c
taskstats.c
test_kprobes.c
time.c
timeconst.pl
timer.c
tracepoint.c
tsacct.c
uid16.c
up.c
user-return-notifier.c
user.c
user_namespace.c
utsname.c
utsname_sysctl.c
wait.c
watchdog.c	bugs, x86: Fix printk levels for panic, softlockups and stack dumps	2012-01-26 21:28:45 +01:00
workqueue.c
workqueue_sched.h