From: Ming Lei <tom.leiming@gmail.com>
Date: Thu, 8 May 2014 07:23:45 +0000 (+0800)
Subject: virtio_scsi: remove ACCESS_ONCE() and smp_read_barrier_depends()
X-Git-Tag: omap-for-v3.16/fixes-against-rc1~13^2~88
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f259d9bdd2fb13926dd16ffacd3417d610c23e8c;p=pandora-kernel.git

virtio_scsi: remove ACCESS_ONCE() and smp_read_barrier_depends()

Access to tgt->req_vq is strictly serialized by spin_lock
of tgt->tgt_lock, so the ACCESS_ONCE() isn't necessary.

smp_read_barrier_depends() in virtscsi_req_done was introduced
to order reading req_vq and decreasing tgt->reqs, but it isn't
needed now because req_vq is read from
scsi->req_vqs[vq->index - VIRTIO_SCSI_VQ_BASE] instead of
tgt->req_vq, so remove the unnecessary barrier.

Also remove related comment about the barrier.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---

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