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>
diff --git a/kernel/exit.c b/kernel/exit.c
index 9220967..4c70c37 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -88,11 +88,12 @@
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:
