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From: Christoph Hellwig <hch@infradead.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
	hch@lst.de, JBottomley@Parallels.com, venkateshs@google.com,
	Ming Lei <tom.leiming@gmail.com>
Subject: Re: [PATCH v3 1/6] virtio_scsi: remove ACCESS_ONCE() and smp_read_barrier_depends()
Date: Thu, 5 Jun 2014 03:11:27 -0700	[thread overview]
Message-ID: <20140605101127.GA8633@infradead.org> (raw)
In-Reply-To: <1401881699-1456-2-git-send-email-pbonzini@redhat.com>

On Wed, Jun 04, 2014 at 01:34:54PM +0200, Paolo Bonzini wrote:
> From: Ming Lei <tom.leiming@gmail.com>
> 
> 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.

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

  reply	other threads:[~2014-06-05 10:11 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-04 11:34 [PATCH v3 0/6] virtio-scsi patches for 3.16 + midlayer fix Paolo Bonzini
2014-06-04 11:34 ` [PATCH v3 1/6] virtio_scsi: remove ACCESS_ONCE() and smp_read_barrier_depends() Paolo Bonzini
2014-06-05 10:11   ` Christoph Hellwig [this message]
2014-06-04 11:34 ` [PATCH v3 2/6] virtio-scsi: replace target spinlock with seqcount Paolo Bonzini
2014-06-04 11:34 ` [PATCH v3 3/6] virtio-scsi: avoid cancelling uninitialized work items Paolo Bonzini
2014-06-05 10:12   ` Christoph Hellwig
2014-06-11 12:47   ` Christoph Hellwig
2014-06-11 13:19     ` Fwd: " Stefan Hajnoczi
2014-06-04 11:34 ` [PATCH v3 4/6] scsi_error: fix invalid setting of host byte Paolo Bonzini
2014-06-05 10:12   ` Christoph Hellwig
2014-06-04 11:34 ` [PATCH v3 5/6] virtio-scsi: fix various bad behavior on aborted requests Paolo Bonzini
2014-06-04 17:29   ` Venkatesh Srinivas
2014-06-04 19:05     ` Paolo Bonzini
2014-06-05  3:10       ` Venkatesh Srinivas
2014-06-04 11:34 ` [PATCH v3 6/6] virtio-scsi: Implement change_queue_depth for virtscsi targets Paolo Bonzini

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