exit: avoid sig->count in de_thread/__exit_signal synchronization
de_thread() and __exit_signal() use signal_struct->count/notify_count for
synchronization. We can simplify the code and use ->notify_count only.
Instead of comparing these two counters, we can change de_thread() to set
->notify_count = nr_of_sub_threads, then change __exit_signal() to
dec-and-test this counter and notify group_exit_task.
Note that __exit_signal() checks "notify_count > 0" just for symmetry with
exit_notify(), we could just check it is != 0.
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/fs/exec.c b/fs/exec.c
index 0c72d23..e19de6a 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -768,7 +768,6 @@
struct signal_struct *sig = tsk->signal;
struct sighand_struct *oldsighand = tsk->sighand;
spinlock_t *lock = &oldsighand->siglock;
- int count;
if (thread_group_empty(tsk))
goto no_thread_group;
@@ -785,13 +784,13 @@
spin_unlock_irq(lock);
return -EAGAIN;
}
- sig->group_exit_task = tsk;
- zap_other_threads(tsk);
- /* Account for the thread group leader hanging around: */
- count = thread_group_leader(tsk) ? 1 : 2;
- sig->notify_count = count;
- while (atomic_read(&sig->count) > count) {
+ sig->group_exit_task = tsk;
+ sig->notify_count = zap_other_threads(tsk);
+ if (!thread_group_leader(tsk))
+ sig->notify_count--;
+
+ while (sig->notify_count) {
__set_current_state(TASK_UNINTERRUPTIBLE);
spin_unlock_irq(lock);
schedule();
