[PATCH 122/270] libceph: fix mutex coverage for ceph_con_close

Herton Ronaldo Krzesinski herton.krzesinski at canonical.com
Mon Nov 26 16:56:52 UTC 2012


3.5.7u1 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sage Weil <sage at inktank.com>

commit 8c50c817566dfa4581f82373aac39f3e608a7dc8 upstream.

Hold the mutex while twiddling all of the state bits to avoid possible
races.  While we're here, make not of why we cannot close the socket
directly.

Signed-off-by: Sage Weil <sage at inktank.com>
Reviewed-by: Alex Elder <elder at inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda at inktank.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 net/ceph/messenger.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 6e2f678..e65b15d 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -503,6 +503,7 @@ static void reset_connection(struct ceph_connection *con)
  */
 void ceph_con_close(struct ceph_connection *con)
 {
+	mutex_lock(&con->mutex);
 	dout("con_close %p peer %s\n", con,
 	     ceph_pr_addr(&con->peer_addr.in_addr));
 	clear_bit(NEGOTIATING, &con->state);
@@ -515,11 +516,16 @@ void ceph_con_close(struct ceph_connection *con)
 	clear_bit(KEEPALIVE_PENDING, &con->flags);
 	clear_bit(WRITE_PENDING, &con->flags);
 
-	mutex_lock(&con->mutex);
 	reset_connection(con);
 	con->peer_global_seq = 0;
 	cancel_delayed_work(&con->work);
 	mutex_unlock(&con->mutex);
+
+	/*
+	 * We cannot close the socket directly from here because the
+	 * work threads use it without holding the mutex.  Instead, let
+	 * con_work() do it.
+	 */
 	queue_con(con);
 }
 EXPORT_SYMBOL(ceph_con_close);
-- 
1.7.9.5





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