[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, 0 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 9bbd3b4e76dc..d84c9a2c4b8f 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -609,6 +609,7 @@ static inline int de_thread(struct task_struct *tsk)
 		count = 1;
 	while (atomic_read(&oldsig->count) > count) {
 		oldsig->group_exit_task = current;
+		oldsig->notify_count = count;
 		__set_current_state(TASK_UNINTERRUPTIBLE);
 		spin_unlock_irq(lock);
 		schedule();