linux-kernel - [PATCH 2/2] aio: fix kioctx not being freed after cancellation at exit time

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Message-ID: <20130213174636.GA20008@kvack.org>
Date:	Wed, 13 Feb 2013 12:46:36 -0500
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Kent Overstreet <koverstreet@...gle.com>
Cc:	linux-aio@...ck.org, linux-fsdevel@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/2] aio: fix kioctx not being freed after cancellation at exit time

The recent changes overhauling fs/aio.c introduced a bug that results in the
kioctx not being freed when outstanding kiocbs are cancelled at exit_aio()
time.  Specifically, a kiocb that is cancelled has its completion events
discarded by batch_complete_aio(), which then fails to wake up the process
stuck in free_ioctx().  Fix this by adding a wake_up() in batch_complete_aio()
and modifying the wait_event() condition in free_ioctx() appropriately.

Signed-off-by: Benjamin LaHaise <bcrl@...ck.org>
---
 fs/aio.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index dc52b0c..46f9dd0 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -335,7 +335,9 @@ static void free_ioctx(struct kioctx *ctx)
 	kunmap_atomic(ring);
 
 	while (atomic_read(&ctx->reqs_available) < ctx->nr) {
-		wait_event(ctx->wait, head != ctx->shadow_tail);
+		wait_event(ctx->wait,
+			   (head != ctx->shadow_tail) ||
+			   (atomic_read(&ctx->reqs_available) != ctx->nr));
 
 		avail = (head <= ctx->shadow_tail ?
 			 ctx->shadow_tail : ctx->nr) - head;
@@ -754,6 +756,7 @@ void batch_complete_aio(struct batch_complete *batch)
 			 * with free_ioctx()
 			 */
 			atomic_inc(&req->ki_ctx->reqs_available);
+			wake_up(&req->ki_ctx->wait);
 			aio_put_req(req);
 			continue;
 		}
-- 
1.7.4.1


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