On Sat, Apr 27, 2013 at 11:16:49AM +0800, Asias He wrote:
> Unlike tcm_vhost_evt requests, tcm_vhost_cmd requests are passed to the
> target core system, we can not make sure all the pending requests will
> be finished by flushing the virt queue.
>
> In this patch, we do refcount for every tcm_vhost_cmd requests to make
> vhost_scsi_flush() wait for all the pending requests issued before the
> flush operation to be finished.
>
> This is useful when we call vhost_scsi_clear_endpoint() to stop
> tcm_vhost. No new requests will be passed to target core system because
> we clear the endpoint by setting vs_tpg to NULL. And we wait for all the
> old requests. These guarantee no requests will be leaked and existing
> requests will be completed.
>
> Signed-off-by: Asias He <asias@xxxxxxxxxx>
> ---
> drivers/vhost/tcm_vhost.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++-
> drivers/vhost/tcm_vhost.h | 3 ++
> 2 files changed, 92 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> index 99d3480..afb5308 100644
> --- a/drivers/vhost/tcm_vhost.c
> +++ b/drivers/vhost/tcm_vhost.c
> @@ -74,8 +74,19 @@ enum {
> #define VHOST_SCSI_MAX_VQ 128
> #define VHOST_SCSI_MAX_EVENT 128
>
> +struct vhost_scsi_inflight {
> + /* Wait for the flush operation to finish */
> + struct completion comp;
> + /* Refcount for the inflight reqs */
> + struct kref kref;
> +};
> +
> struct vhost_scsi_virtqueue {
> struct vhost_virtqueue vq;
> + /* Track inflight reqs, protected by vq->mutex */
Actually, it's protected by dev mutex: you drop
vq mutex before flush.
> + struct vhost_scsi_inflight inflights[2];
> + /* Indicate current inflight in use, protected by vq->mutex */
> + int inflight_idx;
> };
>
I'd be happier with a dynamically allocated inflights,
and simply pass it in to vhost_scsi_flush.
I guess we can do this in a follow-up cleanup.
> struct vhost_scsi {
> @@ -111,6 +122,59 @@ static int iov_num_pages(struct iovec *iov)
> ((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT;
> }
>
> +void tcm_vhost_done_inflight(struct kref *kref)
> +{
> + struct vhost_scsi_inflight *inflight;
> +
> + inflight = container_of(kref, struct vhost_scsi_inflight, kref);
> + complete(&inflight->comp);
> +}
> +
> +static void tcm_vhost_init_inflight(struct vhost_scsi *vs,
> + struct vhost_scsi_inflight *old_inflight[])
> +{
> + struct vhost_scsi_inflight *new_inflight;
> + struct vhost_virtqueue *vq;
> + int idx, i;
> +
> + for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
> + vq = &vs->vqs[i].vq;
> +
> + mutex_lock(&vq->mutex);
> +
> + /* store old infight */
> + idx = vs->vqs[i].inflight_idx;
> + if (old_inflight)
> + old_inflight[i] = &vs->vqs[i].inflights[idx];
> +
> + /* setup new infight */
> + vs->vqs[i].inflight_idx = idx ^ 1;
> + new_inflight = &vs->vqs[i].inflights[idx ^ 1];
> + kref_init(&new_inflight->kref);
> + init_completion(&new_inflight->comp);
> +
> + mutex_unlock(&vq->mutex);
> + }
> +}
> +
> +static struct vhost_scsi_inflight *
> +tcm_vhost_get_inflight(struct vhost_virtqueue *vq)
> +{
> + struct vhost_scsi_inflight *inflight;
> + struct vhost_scsi_virtqueue *svq;
> +
> + svq = container_of(vq, struct vhost_scsi_virtqueue, vq);
> + inflight = &svq->inflights[svq->inflight_idx];
> + kref_get(&inflight->kref);
> +
> + return inflight;
> +}
> +
> +static void tcm_vhost_put_inflight(struct vhost_scsi_inflight *inflight)
> +{
> + kref_put(&inflight->kref, tcm_vhost_done_inflight);
> +}
> +
> static int tcm_vhost_check_true(struct se_portal_group *se_tpg)
> {
> return 1;
> @@ -407,6 +471,8 @@ static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
> kfree(tv_cmd->tvc_sgl);
> }
>
> + tcm_vhost_put_inflight(tv_cmd->inflight);
> +
> kfree(tv_cmd);
> }
>
> @@ -533,6 +599,7 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work *work)
> }
>
> static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
> + struct vhost_virtqueue *vq,
> struct tcm_vhost_tpg *tv_tpg,
> struct virtio_scsi_cmd_req *v_req,
> u32 exp_data_len,
> @@ -557,6 +624,7 @@ static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
> tv_cmd->tvc_exp_data_len = exp_data_len;
> tv_cmd->tvc_data_direction = data_direction;
> tv_cmd->tvc_nexus = tv_nexus;
> + tv_cmd->inflight = tcm_vhost_get_inflight(vq);
>
> return tv_cmd;
> }
> @@ -812,7 +880,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
> for (i = 0; i < data_num; i++)
> exp_data_len += vq->iov[data_first + i].iov_len;
>
> - tv_cmd = vhost_scsi_allocate_cmd(tv_tpg, &v_req,
> + tv_cmd = vhost_scsi_allocate_cmd(vq, tv_tpg, &v_req,
> exp_data_len, data_direction);
> if (IS_ERR(tv_cmd)) {
> vq_err(vq, "vhost_scsi_allocate_cmd failed %ld\n",
> @@ -949,12 +1017,29 @@ static void vhost_scsi_flush_vq(struct vhost_scsi *vs, int index)
>
> static void vhost_scsi_flush(struct vhost_scsi *vs)
> {
> + struct vhost_scsi_inflight *old_inflight[VHOST_SCSI_MAX_VQ];
> int i;
>
> + /* Init new inflight and remember the old inflight */
> + tcm_vhost_init_inflight(vs, old_inflight);
> +
> + /*
> + * The inflight->kref was initialized to 1. We decrement it here to
> + * indicate the start of the flush operation so that it will reach 0
> + * when all the reqs are finished.
> + */
> + for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
> + kref_put(&old_inflight[i]->kref, tcm_vhost_done_inflight);
> +
> + /* Flush both the vhost poll and vhost work */
> for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
> vhost_scsi_flush_vq(vs, i);
> vhost_work_flush(&vs->dev, &vs->vs_completion_work);
> vhost_work_flush(&vs->dev, &vs->vs_event_work);
> +
> + /* Wait for all reqs issued before the flush to be finished */
> + for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
> + wait_for_completion(&old_inflight[i]->comp);
> }
>
> /*
> @@ -1185,6 +1270,9 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
> s->vqs[i].vq.handle_kick = vhost_scsi_handle_kick;
> }
> r = vhost_dev_init(&s->dev, vqs, VHOST_SCSI_MAX_VQ);
> +
> + tcm_vhost_init_inflight(s, NULL);
> +
> if (r < 0) {
> kfree(vqs);
> kfree(s);
> diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
> index 514b9fd..26a57c2 100644
> --- a/drivers/vhost/tcm_vhost.h
> +++ b/drivers/vhost/tcm_vhost.h
> @@ -2,6 +2,7 @@
> #define TCM_VHOST_NAMELEN 256
> #define TCM_VHOST_MAX_CDB_SIZE 32
>
> +struct vhost_scsi_inflight;
> struct tcm_vhost_cmd {
> /* Descriptor from vhost_get_vq_desc() for virt_queue segment */
> int tvc_vq_desc;
> @@ -37,6 +38,8 @@ struct tcm_vhost_cmd {
> unsigned char tvc_sense_buf[TRANSPORT_SENSE_BUFFER];
> /* Completed commands list, serviced from vhost worker thread */
> struct llist_node tvc_completion_list;
> + /* Used to track inflight cmd */
> + struct vhost_scsi_inflight *inflight;
> };
>
> struct tcm_vhost_nexus {
> --
> 1.8.1.4
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