From: David Teigland <teigland@redhat.com>
Date: Thu, 18 Jun 2009 18:20:24 +0000 (-0500)
Subject: dlm: fix plock use-after-free
X-Git-Tag: v2.6.31-rc4~49^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c78a87d0a1fc885dfdbe21fd5e07787691dfb068;p=pandora-kernel.git

dlm: fix plock use-after-free

Fix a regression from the original addition of nfs lock support
586759f03e2e9031ac5589912a51a909ed53c30a.  When a synchronous
(non-nfs) plock completes, the waiting thread will wake up and
free the op struct.  This races with the user thread in
dev_write() which goes on to read the op's callback field to
check if the lock is async and needs a callback.  This check
can happen on the freed op.  The fix is to note the callback
value before the op can be freed.

Signed-off-by: David Teigland <teigland@redhat.com>
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