linux-kernel - [PATCH 01/21] aio: fix kioctx not being freed after cancellation at exit time

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Date:	Mon, 13 May 2013 18:18:38 -0700
From:	Kent Overstreet <koverstreet@...gle.com>
To:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-aio@...ck.org
Cc:	akpm@...ux-foundation.org, Benjamin LaHaise <bcrl@...ck.org>,
	Kent Overstreet <koverstreet@...gle.com>,
	Josh Boyer <jwboyer@...hat.com>, Zach Brown <zab@...hat.com>
Subject: [PATCH 01/21] aio: fix kioctx not being freed after cancellation at exit time

From: Benjamin LaHaise <bcrl@...ck.org>

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 modifying the wait_event() condition
in free_ioctx() appropriately.

This patch was tested with the cancel operation in the thread based code
posted yesterday.

Signed-off-by: Benjamin LaHaise <bcrl@...ck.org>
Signed-off-by: Kent Overstreet <koverstreet@...gle.com>
Cc: Kent Overstreet <koverstreet@...gle.com>
Cc: Josh Boyer <jwboyer@...hat.com>
Cc: Zach Brown <zab@...hat.com>
---
 fs/aio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/aio.c b/fs/aio.c
index c5b1a8c..fe794af 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -307,7 +307,9 @@ static void free_ioctx(struct kioctx *ctx)
 	kunmap_atomic(ring);
 
 	while (atomic_read(&ctx->reqs_active) > 0) {
-		wait_event(ctx->wait, head != ctx->tail);
+		wait_event(ctx->wait,
+			   (head != ctx->tail) ||
+			   (atomic_read(&ctx->reqs_active) <= 0);
 
 		avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
 
-- 
1.8.2.1

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