libceph: avoid NULL kref_put when osd reset races with alloc_msg
The ceph_on_in_msg_alloc() method drops con->mutex while it allocates a
message. If that races with a timeout that resends a zillion messages and
resets the connection, and the ->alloc_msg() method returns a NULL message,
it will call ceph_msg_put(NULL) and BUG.
Fix by only calling put if msg is non-NULL.
Fixes http://tracker.newdream.net/issues/3142
Signed-off-by: Sage Weil <sage@inktank.com>
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index cad0d17..3ef1759 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -2750,7 +2750,8 @@
msg = con->ops->alloc_msg(con, hdr, skip);
mutex_lock(&con->mutex);
if (con->state != CON_STATE_OPEN) {
- ceph_msg_put(msg);
+ if (msg)
+ ceph_msg_put(msg);
return -EAGAIN;
}
con->in_msg = msg;
