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SubjectRe: [PATCH 2/3] virtio_blk: avoid repeating vblk->vqs[qid]
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在 2021/5/20 下午10:13, Stefan Hajnoczi 写道:
> struct virtio_blk_vq is accessed in many places. Introduce "vbq" local
> variables to avoid repeating vblk->vqs[qid] throughout the code. The
> patches that follow will add more accesses, making the payoff even
> greater.
>
> virtio_commit_rqs() calls the local variable "vq", which is easily
> confused with struct virtqueue. Rename to "vbq" for clarity.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
> drivers/block/virtio_blk.c | 34 +++++++++++++++++-----------------
> 1 file changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index b9fa3ef5b57c..fc0fb1dcd399 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -174,16 +174,16 @@ static inline void virtblk_request_done(struct request *req)
> static void virtblk_done(struct virtqueue *vq)
> {
> struct virtio_blk *vblk = vq->vdev->priv;
> + struct virtio_blk_vq *vbq = &vblk->vqs[vq->index];
> bool req_done = false;
> - int qid = vq->index;
> struct virtblk_req *vbr;
> unsigned long flags;
> unsigned int len;
>
> - spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
> + spin_lock_irqsave(&vbq->lock, flags);
> do {
> virtqueue_disable_cb(vq);
> - while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
> + while ((vbr = virtqueue_get_buf(vq, &len)) != NULL) {
> struct request *req = blk_mq_rq_from_pdu(vbr);
>
> if (likely(!blk_should_fake_timeout(req->q)))
> @@ -197,32 +197,32 @@ static void virtblk_done(struct virtqueue *vq)
> /* In case queue is stopped waiting for more buffers. */
> if (req_done)
> blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
> - spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
> + spin_unlock_irqrestore(&vbq->lock, flags);
> }
>
> static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx)
> {
> struct virtio_blk *vblk = hctx->queue->queuedata;
> - struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num];
> + struct virtio_blk_vq *vbq = &vblk->vqs[hctx->queue_num];
> bool kick;
>
> - spin_lock_irq(&vq->lock);
> - kick = virtqueue_kick_prepare(vq->vq);
> - spin_unlock_irq(&vq->lock);
> + spin_lock_irq(&vbq->lock);
> + kick = virtqueue_kick_prepare(vbq->vq);
> + spin_unlock_irq(&vbq->lock);
>
> if (kick)
> - virtqueue_notify(vq->vq);
> + virtqueue_notify(vbq->vq);
> }
>
> static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
> const struct blk_mq_queue_data *bd)
> {
> struct virtio_blk *vblk = hctx->queue->queuedata;
> + struct virtio_blk_vq *vbq = &vblk->vqs[hctx->queue_num];
> struct request *req = bd->rq;
> struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
> unsigned long flags;
> unsigned int num;
> - int qid = hctx->queue_num;
> int err;
> bool notify = false;
> bool unmap = false;
> @@ -274,16 +274,16 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
> vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_IN);
> }
>
> - spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
> - err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num);
> + spin_lock_irqsave(&vbq->lock, flags);
> + err = virtblk_add_req(vbq->vq, vbr, vbr->sg, num);
> if (err) {
> - virtqueue_kick(vblk->vqs[qid].vq);
> + virtqueue_kick(vbq->vq);
> /* Don't stop the queue if -ENOMEM: we may have failed to
> * bounce the buffer due to global resource outage.
> */
> if (err == -ENOSPC)
> blk_mq_stop_hw_queue(hctx);
> - spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
> + spin_unlock_irqrestore(&vbq->lock, flags);
> switch (err) {
> case -ENOSPC:
> return BLK_STS_DEV_RESOURCE;
> @@ -294,12 +294,12 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
> }
> }
>
> - if (bd->last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
> + if (bd->last && virtqueue_kick_prepare(vbq->vq))
> notify = true;
> - spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
> + spin_unlock_irqrestore(&vbq->lock, flags);
>
> if (notify)
> - virtqueue_notify(vblk->vqs[qid].vq);
> + virtqueue_notify(vbq->vq);
> return BLK_STS_OK;
> }
>

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