linux-kernel - [PATCH] Fix __wait_on_atomic_t() to call the action func if the counter != 0

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Message-ID: <20130723154924.24306.42326.stgit@warthog.procyon.org.uk>
Date:	Tue, 23 Jul 2013 16:49:24 +0100
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...ux-foundation.org
Cc:	linux-nfs@...r.kernel.org, Jeff Layton <jlayton@...hat.com>,
	linux-kernel@...r.kernel.org, linux-cachefs@...hat.com,
	Milosz Tanski <milosz@...in.com>,
	Yacine Belkadi <yacine.belkadi.1@...il.com>
Subject: [PATCH] Fix __wait_on_atomic_t() to call the action func if the
 counter != 0

Fix __wait_on_atomic_t() so that it calls the action func if the counter != 0
rather than if the counter is 0 so as to be analogous to __wait_on_bit().

Thanks to Yacine who found this by visual inspection.

This will affect FS-Cache in that it will could fail to sleep correctly when
trying to clean up after a netfs cookie is withdrawn.

Reported-by: Yacine Belkadi <yacine.belkadi.1@...il.com>
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Yacine Belkadi <yacine.belkadi.1@...il.com>
cc: Milosz Tanski <milosz@...in.com>
cc: Jeff Layton <jlayton@...hat.com>
---

 kernel/wait.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/wait.c b/kernel/wait.c
index ce0daa3..dec68bd 100644
--- a/kernel/wait.c
+++ b/kernel/wait.c
@@ -333,7 +333,8 @@ int __wait_on_atomic_t(wait_queue_head_t *wq, struct wait_bit_queue *q,
 		prepare_to_wait(wq, &q->wait, mode);
 		val = q->key.flags;
 		if (atomic_read(val) == 0)
-			ret = (*action)(val);
+			break;
+		ret = (*action)(val);
 	} while (!ret && atomic_read(val) != 0);
 	finish_wait(wq, &q->wait);
 	return ret;

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