do_wait() wakeup optimization: change __wake_up_parent() to use filtered wakeup

Ratan Nalumasu reported that in a process with many threads doing
unnecessary wakeups.  Every waiting thread in the process wakes up to loop
through the children and see that the only ones it cares about are still
not ready.

Now that we have struct wait_opts we can change do_wait/__wake_up_parent
to use filtered wakeups.

We can make child_wait_callback() more clever later, right now it only
checks eligible_child().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ratan Nalumasu <rnalumasu@gmail.com>
Cc: Vitaly Mayatskikh <vmayatsk@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Tested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 417f7c9..bb230d5 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2411,7 +2411,7 @@ static void selinux_bprm_committed_creds(struct linux_binprm *bprm)
 	/* Wake up the parent if it is waiting so that it can recheck
 	 * wait permission to the new task SID. */
 	read_lock(&tasklist_lock);
-	wake_up_interruptible(&current->real_parent->signal->wait_chldexit);
+	__wake_up_parent(current, current->real_parent);
 	read_unlock(&tasklist_lock);
 }