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libceph: avoid NULL kref_put from NULL alloc_msg return

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The ceph_on_in_msg_alloc() method calls the ->alloc_msg() helper which
may return NULL.  It also drops con->mutex while it allocates a message,
which means that the connection state may change (e.g., get closed).  If
that happens, we clean up and bail out.  Avoid calling ceph_msg_put() on
a NULL return value and triggering a crash.

This was observed when an ->alloc_msg() call races with a timeout that
resends a zillion messages and resets the connection, and ->alloc_msg()
returns NULL (because the request was resent to another target).

Fixes http://tracker.newdream.net/issues/3342

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
This commit is contained in:
Sage Weil 2012-10-25 08:49:41 -07:00 committed by Alex Elder
parent 0f9831a893
commit 7246240c7c
1 changed files with 2 additions and 1 deletions
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3
net/ceph/messenger.c
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@ -2742,7 +2742,8 @@ static int ceph_con_in_msg_alloc(struct ceph_connection *con, int *skip)
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;