Il 08/05/2014 07:24, Ming Lei ha scritto:
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
On Thu, May 8, 2014 at 3:05 PM, Paolo Bonzini pbonz...@redhat.com wrote:
Decrements of reqs are never concurrent with writes of req_vq: before the
decrement reqs will be != 0; after the decrement the virtqueue completion
routine will not use the req_vq so it can be changed by a new request.
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
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