tree bf7bebecdcd53aa75f80fb1e066f2293a2483916
parent ed30bf317c5ceb25166cdbce3e0b35e33c82b509
author Li Dongyang <lidongyang@novell.com> 1315980160 +0800
committer Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> 1318513712 -0400

xen-blkfront: fix a deadlock while handling discard response

When we get -EOPNOTSUPP response for a discard request, we will clear
the discard flag on the request queue so we won't attempt to send discard
requests to backend again, and this should be protected under rq->queue_lock.
However, when we setup the request queue, we pass blkif_io_lock to
blk_init_queue so rq->queue_lock is blkif_io_lock indeed, and this lock
is already taken when we are in blkif_interrpt, so remove the
spin_lock/spin_unlock when we clear the discard flag or we will end up
with deadlock here

Signed-off-by: Li Dongyang <lidongyang@novell.com>
[v1: Updated description a bit and removed comment from source]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>