[PATCH] add notify_count for de_thread

From: Manfred Spraul <manfred@colorfullife.com>

de_thread is called by exec to kill all threads in the thread group except
the threads required for exec.

The waiting is implemented by waiting for a wakeup from __exit_signal: If
the reference count is less or equal to 2, then the waiter is woken up.  If
exec is called by a non-leader thread, then two threads are required for
exec.

But if a thread group leader calls exec, then only one thread is required
for exec.  Thus the hardcoded "2" leads to a superfluous wakeup.  The patch
fixes that by adding a "notify_count" field to the signal structure.

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 3560d7da7032..d1f02ea4b7b1 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -336,7 +336,7 @@ void __exit_signal(struct task_struct *tsk)
 		 * If there is any task waiting for the group exit
 		 * then notify it:
 		 */
-		if (sig->group_exit_task && atomic_read(&sig->count) <= 2) {
+		if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
 			wake_up_process(sig->group_exit_task);
 			sig->group_exit_task = NULL;
 		}