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authorOleg Nesterov <oleg@redhat.com>2013-04-30 15:28:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-30 17:04:06 -0700
commitdc7ee2aac830e5423f41de87d50441f138f648da (patch)
tree735a75c2d2455721dffed758632f07f62cbf2206 /fs
parent079148b919d0c58b796f9ae98bdb53028dbcd5e7 (diff)
downloadlinux-dc7ee2aac830e5423f41de87d50441f138f648da.tar.gz
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 <oleg@redhat.com> Acked-by: Mandeep Singh Baines <msb@chromium.org> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/coredump.c15
1 files changed, 9 insertions, 6 deletions
diff --git a/fs/coredump.c b/fs/coredump.c
index 7300e312fb3..ec306cc9a28 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);
-
}
/*