Guillaume Morin ef9823939e kernel/exit.c: call proc_exit_connector() after exit_state is set ... The process events connector delivers a notification when a process exits. This is really convenient for a process that spawns and wants to monitor its children through an epoll-able() interface. Unfortunately, there is a small window between when the event is delivered and the child become wait()-able. This is creates a race if the parent wants to make sure that it knows about the exit, e.g pid_t pid = fork(); if (pid > 0) { register_interest_for_pid(pid); if (waitpid(pid, NULL, WNOHANG) > 0) { /* We might have raced with exit() */ } return; } /* Child */ execve(...) register_interest_for_pid() would be telling the the connector socket reader to pay attention to events related to pid. Though this is not a bug, I think it would make the connector a bit more usable if this race was closed by simply moving the call to proc_exit_connector() from just before exit_notify() to right after. Oleg said: : Even with this patch the code above is still "racy" if the child is : multi-threaded. Plus it should obviously filter-out subthreads. And : afaics there is no way to make it reliable, even if you change the code : above so that waitpid() is called only after the last thread exits WNOHANG : still can fail. Signed-off-by: Guillaume Morin <guillaume@morinfr.org> Cc: Matt Helsley <matt.helsley@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2014-04-07 16:36:04 -07:00
..
debug	mm: per-thread vma caching	2014-04-07 16:35:53 -07:00
events	Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm	2014-04-05 13:20:43 -07:00
gcov
irq	genirq: Export symbol no_action()	2014-03-22 11:33:09 +01:00
locking	Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-03-31 14:13:25 -07:00
power	Merge branches 'pm-runtime' and 'pm-sleep'	2014-03-20 13:25:54 +01:00
printk	printk: fix one circular lockdep warning about console_lock	2014-04-03 16:21:08 -07:00
rcu	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-03-31 11:21:19 -07:00
sched	Merge branch 'akpm' (incoming from Andrew)	2014-04-03 16:22:16 -07:00
time	Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-04-01 11:00:07 -07:00
trace	Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm	2014-04-05 13:20:43 -07:00
.gitignore
acct.c
async.c
audit.c	AUDIT: Allow login in non-init namespaces	2014-03-30 17:02:53 -07:00
audit.h	audit: Use struct net not pid_t to remember the network namespce to reply in	2014-02-28 04:04:33 -08:00
audit_tree.c	inotify: Fix reporting of cookies for inotify events	2014-02-18 11:17:17 +01:00
audit_watch.c	inotify: Fix reporting of cookies for inotify events	2014-02-18 11:17:17 +01:00
auditfilter.c	audit: Update kdoc for audit_send_reply and audit_list_rules_send	2014-03-08 15:31:54 -08:00
auditsc.c	execve: use 'struct filename *' for executable name passing	2014-02-05 12:54:53 -08:00
backtracetest.c
bounds.c
capability.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2014-04-03 09:26:18 -07:00
cgroup.c	Merge branch 'for-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2014-04-03 13:05:42 -07:00
cgroup_freezer.c	cgroup: drop const from @buffer of cftype->write_string()	2014-03-19 10:23:54 -04:00
compat.c	Merge branch 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-04-02 12:51:41 -07:00
configs.c
context_tracking.c
cpu.c
cpu_pm.c
cpuset.c	Merge branch 'akpm' (incoming from Andrew)	2014-04-03 16:22:16 -07:00
crash_dump.c
cred.c
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c	kernel/exit.c: call proc_exit_connector() after exit_state is set	2014-04-07 16:36:04 -07:00
extable.c	asmlinkage: Make main_extable_sort_needed visible	2014-02-13 18:13:22 -08:00
fork.c	mm, mempolicy: remove per-process flag	2014-04-07 16:35:54 -07:00
freezer.c
futex.c	Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-03-31 10:59:39 -07:00
futex_compat.c	compat: Get rid of (get|put)_compat_time(val|spec)	2014-02-02 14:09:12 -08:00
groups.c	kernel/groups.c: remove return value of set_groups	2014-04-03 16:21:05 -07:00
hrtimer.c	timer: Remove code redundancy while calling get_nohz_timer_target()	2014-03-20 12:35:46 +01:00
hung_task.c	kernel: audit/fix non-modular users of module_init in core code	2014-04-03 16:21:07 -07:00
irq_work.c	perf/x86: Warn to early_printk() in case irq_work is too slow	2014-02-21 21:49:07 +01:00
itimer.c
jump_label.c
kallsyms.c
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c	kernel: audit/fix non-modular users of module_init in core code	2014-04-03 16:21:07 -07:00
kmod.c	execve: use 'struct filename *' for executable name passing	2014-02-05 12:54:53 -08:00
kprobes.c
ksysfs.c	rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c	2014-02-26 06:35:16 -08:00
kthread.c	kthread: ensure locality of task_struct allocations	2014-04-03 16:20:49 -07:00
latencytop.c
Makefile	Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-03-31 14:13:25 -07:00
module-internal.h
module.c	Nothing major: the stricter permissions checking for sysfs broke	2014-04-06 09:38:07 -07:00
module_signing.c
notifier.c	notifier: Substitute rcu_access_pointer() for rcu_dereference_raw()	2014-02-26 06:35:13 -08:00
nsproxy.c
padata.c
panic.c	Nothing major: the stricter permissions checking for sysfs broke	2014-04-06 09:38:07 -07:00
params.c
pid.c
pid_namespace.c	pid_namespace: pidns_get() should check task_active_pid_ns() != NULL	2014-04-02 16:20:21 -07:00
posix-cpu-timers.c
posix-timers.c
profile.c	kernel: audit/fix non-modular users of module_init in core code	2014-04-03 16:21:07 -07:00
ptrace.c	kernel/compat: convert to COMPAT_SYSCALL_DEFINE	2014-03-06 15:35:10 +01:00
range.c
reboot.c
relay.c	treewide: Fix typo in Documentation/DocBook	2014-02-19 14:58:17 +01:00
res_counter.c	res_counter: remove interface for locked charging and uncharging	2014-04-07 16:35:54 -07:00
resource.c	kernel/resource.c: make reallocate_resource() static	2014-04-03 16:21:07 -07:00
seccomp.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2014-04-03 09:26:18 -07:00
signal.c	Merge branch 'master' into for-next	2014-02-20 14:54:28 +01:00
smp.c	smp: Rename __smp_call_function_single() to smp_call_function_single_async()	2014-02-24 14:47:15 -08:00
smpboot.c
smpboot.h
softirq.c	softirq: Add linux/irq.h to make it compile again	2014-03-19 11:28:14 +01:00
stacktrace.c
stop_machine.c	stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus()	2014-03-11 11:33:47 +01:00
sys.c	mm, thp: add VM_INIT_DEF_MASK and PRCTL_THP_DISABLE	2014-04-07 16:35:52 -07:00
sys_ni.c	fs, kernel: permit disabling the uselib syscall	2014-04-03 16:21:05 -07:00
sysctl.c	drop_caches: add some documentation and info message	2014-04-03 16:21:04 -07:00
sysctl_binary.c
system_certificates.S
system_keyring.c
task_work.c
taskstats.c
test_kprobes.c
time.c
timeconst.bc
timer.c	Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-04-01 11:00:07 -07:00
torture.c	rcutorture: Gracefully handle NULL cleanup hooks	2014-02-23 09:04:39 -08:00
tracepoint.c	Nothing major: the stricter permissions checking for sysfs broke	2014-04-06 09:38:07 -07:00
tsacct.c
uid16.c
up.c	smp: Rename __smp_call_function_single() to smp_call_function_single_async()	2014-02-24 14:47:15 -08:00
user-return-notifier.c
user.c	kernel: audit/fix non-modular users of module_init in core code	2014-04-03 16:21:07 -07:00
user_namespace.c	kernel: audit/fix non-modular users of module_init in core code	2014-04-03 16:21:07 -07:00
utsname.c
utsname_sysctl.c
watchdog.c	kernel/watchdog.c: touch_nmi_watchdog should only touch local cpu not every one	2014-04-03 16:20:58 -07:00
workqueue.c	Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-04-01 11:00:07 -07:00
workqueue_internal.h