Adding the command and kicking the virtqueue so far was done one after
another. Make the kick optional, so that we can take into account SCMD_LAST.
We also need a commit_rqs callback to kick the device if blk-mq aborts
the submission before the last request is reached.
Suggested-by: Stefan Hajnoczi <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
---
drivers/scsi/virtio_scsi.c | 55 +++++++++++++++++++++++++++-----------
1 file changed, 40 insertions(+), 15 deletions(-)
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 8af01777d09c..918c811cea95 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -375,14 +375,7 @@ static void virtscsi_event_done(struct virtqueue *vq)
virtscsi_vq_done(vscsi, &vscsi->event_vq, virtscsi_complete_event);
};
-/**
- * virtscsi_add_cmd - add a virtio_scsi_cmd to a virtqueue
- * @vq : the struct virtqueue we're talking about
- * @cmd : command structure
- * @req_size : size of the request buffer
- * @resp_size : size of the response buffer
- */
-static int virtscsi_add_cmd(struct virtqueue *vq,
+static int __virtscsi_add_cmd(struct virtqueue *vq,
struct virtio_scsi_cmd *cmd,
size_t req_size, size_t resp_size)
{
@@ -427,17 +420,39 @@ static int virtscsi_add_cmd(struct virtqueue *vq,
return virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, GFP_ATOMIC);
}
-static int virtscsi_kick_cmd(struct virtio_scsi_vq *vq,
+static void virtscsi_kick_vq(struct virtio_scsi_vq *vq)
+{
+ bool needs_kick;
+ unsigned long flags;
+
+ spin_lock_irqsave(&vq->vq_lock, flags);
+ needs_kick = virtqueue_kick_prepare(vq->vq);
+ spin_unlock_irqrestore(&vq->vq_lock, flags);
+
+ if (needs_kick)
+ virtqueue_notify(vq->vq);
+}
+
+/**
+ * virtscsi_add_cmd - add a virtio_scsi_cmd to a virtqueue, optionally kick it
+ * @vq : the struct virtqueue we're talking about
+ * @cmd : command structure
+ * @req_size : size of the request buffer
+ * @resp_size : size of the response buffer
+ * @kick : whether to kick the virtqueue immediately
+ */
+static int virtscsi_add_cmd(struct virtio_scsi_vq *vq,
struct virtio_scsi_cmd *cmd,
- size_t req_size, size_t resp_size)
+ size_t req_size, size_t resp_size,
+ bool kick)
{
unsigned long flags;
int err;
bool needs_kick = false;
spin_lock_irqsave(&vq->vq_lock, flags);
- err = virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size);
- if (!err)
+ err = __virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size);
+ if (!err && kick)
needs_kick = virtqueue_kick_prepare(vq->vq);
spin_unlock_irqrestore(&vq->vq_lock, flags);
@@ -502,6 +517,7 @@ static int virtscsi_queuecommand(struct Scsi_Host *shost,
struct virtio_scsi *vscsi = shost_priv(shost);
struct virtio_scsi_vq *req_vq = virtscsi_pick_vq_mq(vscsi, sc);
struct virtio_scsi_cmd *cmd = scsi_cmd_priv(sc);
+ bool kick;
unsigned long flags;
int req_size;
int ret;
@@ -531,7 +547,8 @@ static int virtscsi_queuecommand(struct Scsi_Host *shost,
req_size = sizeof(cmd->req.cmd);
}
- ret = virtscsi_kick_cmd(req_vq, cmd, req_size, sizeof(cmd->resp.cmd));
+ kick = (sc->flags & SCMD_LAST) != 0;
+ ret = virtscsi_add_cmd(req_vq, cmd, req_size, sizeof(cmd->resp.cmd), kick);
if (ret == -EIO) {
cmd->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET;
spin_lock_irqsave(&req_vq->vq_lock, flags);
@@ -549,8 +566,8 @@ static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
int ret = FAILED;
cmd->comp = ∁
- if (virtscsi_kick_cmd(&vscsi->ctrl_vq, cmd,
- sizeof cmd->req.tmf, sizeof cmd->resp.tmf) < 0)
+ if (virtscsi_add_cmd(&vscsi->ctrl_vq, cmd,
+ sizeof cmd->req.tmf, sizeof cmd->resp.tmf, true) < 0)
goto out;
wait_for_completion(&comp);
@@ -664,6 +681,13 @@ static int virtscsi_map_queues(struct Scsi_Host *shost)
return blk_mq_virtio_map_queues(qmap, vscsi->vdev, 2);
}
+static void virtscsi_commit_rqs(struct Scsi_Host *shost, u16 hwq)
+{
+ struct virtio_scsi *vscsi = shost_priv(shost);
+
+ virtscsi_kick_vq(&vscsi->req_vqs[hwq]);
+}
+
/*
* The host guarantees to respond to each command, although I/O
* latencies might be higher than on bare metal. Reset the timer
@@ -681,6 +705,7 @@ static struct scsi_host_template virtscsi_host_template = {
.this_id = -1,
.cmd_size = sizeof(struct virtio_scsi_cmd),
.queuecommand = virtscsi_queuecommand,
+ .commit_rqs = virtscsi_commit_rqs,
.change_queue_depth = virtscsi_change_queue_depth,
.eh_abort_handler = virtscsi_abort,
.eh_device_reset_handler = virtscsi_device_reset,
--
2.21.0
On 5/30/19 4:28 AM, Paolo Bonzini wrote:
> @@ -531,7 +547,8 @@ static int virtscsi_queuecommand(struct Scsi_Host *shost,
> req_size = sizeof(cmd->req.cmd);
> }
>
> - ret = virtscsi_kick_cmd(req_vq, cmd, req_size, sizeof(cmd->resp.cmd));
> + kick = (sc->flags & SCMD_LAST) != 0;
> + ret = virtscsi_add_cmd(req_vq, cmd, req_size, sizeof(cmd->resp.cmd), kick);
Have you considered to have the SCSI core call commit_rqs() if bd->last
is true? I think that would avoid that we need to introduce the
SCMD_LAST flag and that would also avoid that every SCSI LLD that
supports a commit_rqs callback has to introduce code to test the
SCMD_LAST flag.
Thanks,
Bart.
On 30/05/19 19:28, Bart Van Assche wrote:
> On 5/30/19 4:28 AM, Paolo Bonzini wrote:
>> @@ -531,7 +547,8 @@ static int virtscsi_queuecommand(struct Scsi_Host
>> *shost,
>> req_size = sizeof(cmd->req.cmd);
>> }
>> - ret = virtscsi_kick_cmd(req_vq, cmd, req_size,
>> sizeof(cmd->resp.cmd));
>> + kick = (sc->flags & SCMD_LAST) != 0;
>> + ret = virtscsi_add_cmd(req_vq, cmd, req_size,
>> sizeof(cmd->resp.cmd), kick);
>
> Have you considered to have the SCSI core call commit_rqs() if bd->last
> is true? I think that would avoid that we need to introduce the
> SCMD_LAST flag and that would also avoid that every SCSI LLD that
> supports a commit_rqs callback has to introduce code to test the
> SCMD_LAST flag.
That is slightly worse for performance, as it unlocks and re-locks the
spinlock.
Paolo
On 5/30/19 1:28 PM, Paolo Bonzini wrote:
> Adding the command and kicking the virtqueue so far was done one after
> another. Make the kick optional, so that we can take into account SCMD_LAST.
> We also need a commit_rqs callback to kick the device if blk-mq aborts
> the submission before the last request is reached.
>
> Suggested-by: Stefan Hajnoczi <[email protected]>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> drivers/scsi/virtio_scsi.c | 55 +++++++++++++++++++++++++++-----------
> 1 file changed, 40 insertions(+), 15 deletions(-)
>
Reviewed-by: Hannes Reinecke <[email protected]>
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
[email protected] +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
On Thu, May 30, 2019 at 7:28 PM Paolo Bonzini <[email protected]> wrote:
>
> Adding the command and kicking the virtqueue so far was done one after
> another. Make the kick optional, so that we can take into account SCMD_LAST.
> We also need a commit_rqs callback to kick the device if blk-mq aborts
> the submission before the last request is reached.
>
> Suggested-by: Stefan Hajnoczi <[email protected]>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> drivers/scsi/virtio_scsi.c | 55 +++++++++++++++++++++++++++-----------
> 1 file changed, 40 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 8af01777d09c..918c811cea95 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -375,14 +375,7 @@ static void virtscsi_event_done(struct virtqueue *vq)
> virtscsi_vq_done(vscsi, &vscsi->event_vq, virtscsi_complete_event);
> };
>
> -/**
> - * virtscsi_add_cmd - add a virtio_scsi_cmd to a virtqueue
> - * @vq : the struct virtqueue we're talking about
> - * @cmd : command structure
> - * @req_size : size of the request buffer
> - * @resp_size : size of the response buffer
> - */
> -static int virtscsi_add_cmd(struct virtqueue *vq,
> +static int __virtscsi_add_cmd(struct virtqueue *vq,
> struct virtio_scsi_cmd *cmd,
> size_t req_size, size_t resp_size)
> {
> @@ -427,17 +420,39 @@ static int virtscsi_add_cmd(struct virtqueue *vq,
> return virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, GFP_ATOMIC);
> }
>
> -static int virtscsi_kick_cmd(struct virtio_scsi_vq *vq,
> +static void virtscsi_kick_vq(struct virtio_scsi_vq *vq)
> +{
> + bool needs_kick;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&vq->vq_lock, flags);
> + needs_kick = virtqueue_kick_prepare(vq->vq);
> + spin_unlock_irqrestore(&vq->vq_lock, flags);
> +
> + if (needs_kick)
> + virtqueue_notify(vq->vq);
> +}
> +
> +/**
> + * virtscsi_add_cmd - add a virtio_scsi_cmd to a virtqueue, optionally kick it
> + * @vq : the struct virtqueue we're talking about
> + * @cmd : command structure
> + * @req_size : size of the request buffer
> + * @resp_size : size of the response buffer
> + * @kick : whether to kick the virtqueue immediately
> + */
> +static int virtscsi_add_cmd(struct virtio_scsi_vq *vq,
> struct virtio_scsi_cmd *cmd,
> - size_t req_size, size_t resp_size)
> + size_t req_size, size_t resp_size,
> + bool kick)
> {
> unsigned long flags;
> int err;
> bool needs_kick = false;
>
> spin_lock_irqsave(&vq->vq_lock, flags);
> - err = virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size);
> - if (!err)
> + err = __virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size);
> + if (!err && kick)
> needs_kick = virtqueue_kick_prepare(vq->vq);
>
> spin_unlock_irqrestore(&vq->vq_lock, flags);
> @@ -502,6 +517,7 @@ static int virtscsi_queuecommand(struct Scsi_Host *shost,
> struct virtio_scsi *vscsi = shost_priv(shost);
> struct virtio_scsi_vq *req_vq = virtscsi_pick_vq_mq(vscsi, sc);
> struct virtio_scsi_cmd *cmd = scsi_cmd_priv(sc);
> + bool kick;
> unsigned long flags;
> int req_size;
> int ret;
> @@ -531,7 +547,8 @@ static int virtscsi_queuecommand(struct Scsi_Host *shost,
> req_size = sizeof(cmd->req.cmd);
> }
>
> - ret = virtscsi_kick_cmd(req_vq, cmd, req_size, sizeof(cmd->resp.cmd));
> + kick = (sc->flags & SCMD_LAST) != 0;
> + ret = virtscsi_add_cmd(req_vq, cmd, req_size, sizeof(cmd->resp.cmd), kick);
> if (ret == -EIO) {
> cmd->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET;
> spin_lock_irqsave(&req_vq->vq_lock, flags);
> @@ -549,8 +566,8 @@ static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
> int ret = FAILED;
>
> cmd->comp = ∁
> - if (virtscsi_kick_cmd(&vscsi->ctrl_vq, cmd,
> - sizeof cmd->req.tmf, sizeof cmd->resp.tmf) < 0)
> + if (virtscsi_add_cmd(&vscsi->ctrl_vq, cmd,
> + sizeof cmd->req.tmf, sizeof cmd->resp.tmf, true) < 0)
> goto out;
>
> wait_for_completion(&comp);
> @@ -664,6 +681,13 @@ static int virtscsi_map_queues(struct Scsi_Host *shost)
> return blk_mq_virtio_map_queues(qmap, vscsi->vdev, 2);
> }
>
> +static void virtscsi_commit_rqs(struct Scsi_Host *shost, u16 hwq)
> +{
> + struct virtio_scsi *vscsi = shost_priv(shost);
> +
> + virtscsi_kick_vq(&vscsi->req_vqs[hwq]);
> +}
> +
> /*
> * The host guarantees to respond to each command, although I/O
> * latencies might be higher than on bare metal. Reset the timer
> @@ -681,6 +705,7 @@ static struct scsi_host_template virtscsi_host_template = {
> .this_id = -1,
> .cmd_size = sizeof(struct virtio_scsi_cmd),
> .queuecommand = virtscsi_queuecommand,
> + .commit_rqs = virtscsi_commit_rqs,
> .change_queue_depth = virtscsi_change_queue_depth,
> .eh_abort_handler = virtscsi_abort,
> .eh_device_reset_handler = virtscsi_device_reset,
> --
> 2.21.0
>
Reviewed-by: Ming Lei <[email protected]>
Thanks,
Ming Lei