linux-kernel - [PATCH] coredump: wait on the core pattern umh at least once

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Message-Id: <1319832688-30336-1-git-send-email-scott@netsplit.com>
Date:	Fri, 28 Oct 2011 13:11:28 -0700
From:	Scott James Remnant <scott@...split.com>
To:	linux-kernel@...r.kernel.org
Cc:	Mandeep Singh Baines <msb@...omium.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Neil Horman <nhorman@...driver.com>,
	Scott James Remnant <scott@...split.com>
Subject: [PATCH] coredump: wait on the core pattern umh at least once

If a thread crashes as a result of a signal on the thread group leader
that signal can still be pending, which means the loop in
wait_for_dump_helpers() falls straight though.

This can mean that the crashing process is reaped before any core
pattern user-mode helper is run, leaving it without entries in /proc
to look through.

While the helper obviously has to deal with that, tweaking this loop
so it runs at least one iteration even in that case helps a lot.

Signed-off-by: Scott James Remnant <scott@...split.com>
---
 fs/exec.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 25dcbe5..8959d304 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -2030,11 +2030,11 @@ static void wait_for_dump_helpers(struct file *file)
 	pipe->readers++;
 	pipe->writers--;
 
-	while ((pipe->readers > 1) && (!signal_pending(current))) {
+	do {
 		wake_up_interruptible_sync(&pipe->wait);
 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 		pipe_wait(pipe);
-	}
+	} while ((pipe->readers > 1) && (!signal_pending(current)));
 
 	pipe->readers--;
 	pipe->writers++;
-- 
1.7.3.1

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