From: Sage Weil <sage@inktank.com>
Date: Thu, 25 Oct 2012 15:49:41 +0000 (-0700)
Subject: libceph: avoid NULL kref_put from NULL alloc_msg return
X-Git-Tag: v3.8-rc1~21^2~60
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7246240c7c186542f73af4fadc744d66440f616f;p=pandora-kernel.git

libceph: avoid NULL kref_put from NULL alloc_msg return

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>
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