From dc7ee2aac830e5423f41de87d50441f138f648da Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 30 Apr 2013 15:28:17 -0700 Subject: [PATCH] coredump: change wait_for_dump_helpers() to use wait_event_interruptible() wait_for_dump_helpers() calls wake_up/kill_fasync from inside the wait_event-like loop. This is not needed and in fact this is not strictly correct, we can/should do this only once after we change pipe->writers. We could even check if it becomes zero. Change this code to use use wait_event_interruptible(), this can also help to make this wait freezable. With this patch we check pipe->readers without pipe_lock(), this is fine. Once we see pipe->readers == 1 we know that the handler decremented the counter, this is all we need. Signed-off-by: Oleg Nesterov Acked-by: Mandeep Singh Baines Cc: Neil Horman Cc: "Rafael J. Wysocki" Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/coredump.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 7300e312fb3a..ec306cc9a28a 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -439,17 +439,20 @@ static void wait_for_dump_helpers(struct file *file) pipe_lock(pipe); pipe->readers++; pipe->writers--; + wake_up_interruptible_sync(&pipe->wait); + kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); + pipe_unlock(pipe); - while ((pipe->readers > 1) && (!signal_pending(current))) { - wake_up_interruptible_sync(&pipe->wait); - kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); - pipe_wait(pipe); - } + /* + * We actually want wait_event_freezable() but then we need + * to clear TIF_SIGPENDING and improve dump_interrupted(). + */ + wait_event_interruptible(pipe->wait, pipe->readers == 1); + pipe_lock(pipe); pipe->readers--; pipe->writers++; pipe_unlock(pipe); - } /* -- GitLab