exit: avoid sig->count in __exit_signal() to detect the group-dead case

Change __exit_signal() to check thread_group_leader() instead of
atomic_dec_and_test(&sig->count).  This must be equivalent, the group
leader must be released only after all other threads have exited and
passed __exit_signal().

Henceforth sig->count is not actually used, except in fs/proc for
get_nr_threads/etc.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2010-05-26 14:43:12 -07:00 committed by Linus Torvalds
parent d344193a05
commit 4a59994297

View file

@ -88,11 +88,12 @@ static void __exit_signal(struct task_struct *tsk)
rcu_read_lock_held() ||
lockdep_tasklist_lock_is_held());
spin_lock(&sighand->siglock);
atomic_dec(&sig->count);
posix_cpu_timers_exit(tsk);
if (atomic_dec_and_test(&sig->count))
if (thread_group_leader(tsk)) {
posix_cpu_timers_exit_group(tsk);
else {
} else {
/*
* If there is any task waiting for the group exit
* then notify it: