On Tue, Mar 05, 2013 at 05:17:07PM +0800, Asias He
wrote:> In commit 365a7150094 ([SCSI] virtio-scsi: hotplug support for
> virtio-scsi), hotplug support is added to virtio-scsi.
>
> This patch adds hotplug and hotunplug support to tcm_vhost.
>
> You can create or delate a LUN in targetcli to hotplug or hotplug a LUN
> in guest.
>
> Signed-off-by: Asias He <asias at redhat.com>
> ---
> drivers/vhost/tcm_vhost.c | 171
++++++++++++++++++++++++++++++++++++++++++++--
> drivers/vhost/tcm_vhost.h | 9 +++
> 2 files changed, 175 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> index 9951297..6693695 100644
> --- a/drivers/vhost/tcm_vhost.c
> +++ b/drivers/vhost/tcm_vhost.c
> @@ -63,6 +63,8 @@ enum {
> #define VHOST_SCSI_MAX_TARGET 256
> #define VHOST_SCSI_MAX_VQ 128
>
> +#define VHOST_SCSI_FEATURES (VHOST_FEATURES | (1ULL <<
VIRTIO_SCSI_F_HOTPLUG))
> +
> struct vhost_scsi {
> /* Protected by vhost_scsi->dev.mutex */
> struct tcm_vhost_tpg *vs_tpg[VHOST_SCSI_MAX_TARGET];
> @@ -74,6 +76,11 @@ struct vhost_scsi {
>
> struct vhost_work vs_completion_work; /* cmd completion work item */
> struct llist_head vs_completion_list; /* cmd completion queue */
> +
> + struct vhost_work vs_event_work; /* evt injection work item */
> + struct llist_head vs_event_list; /* evt injection queue */
> +
> + bool vs_events_dropped;
Documentation pls.
Also - how is this handled during migration?
Don't we need a way for userspace to retrieve this bit?
> };
>
> /* Local pointer to allocated TCM configfs fabric module */
> @@ -341,6 +348,23 @@ static int tcm_vhost_queue_tm_rsp(struct se_cmd
*se_cmd)
> return 0;
> }
>
> +static void tcm_vhost_free_evt(struct tcm_vhost_evt *evt)
> +{
> + kfree(evt);
> +}
> +
> +static struct tcm_vhost_evt *tcm_vhost_allocate_evt(u32 event, u32 reason)
> +{
> + struct tcm_vhost_evt *evt;
> +
> + evt = kzalloc(sizeof(*evt), GFP_KERNEL);
And if this fails?
> +
> + evt->event.event = event;
> + evt->event.reason = reason;
> +
> + return evt;
> +}
> +
> static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
> {
> struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> @@ -359,6 +383,71 @@ static void vhost_scsi_free_cmd(struct tcm_vhost_cmd
*tv_cmd)
> kfree(tv_cmd);
> }
>
> +static void tcm_vhost_do_evt_work(struct vhost_scsi *vs,
> + struct virtio_scsi_event *event)
> +{
> + struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT];
> + struct virtio_scsi_event __user *eventp;
> + unsigned out, in;
> + int head, ret;
> +
> + if (!vs || !vs->vs_endpoint)
> + return;
> +
> + mutex_lock(&vq->mutex);
> +again:
> + vhost_disable_notify(&vs->dev, vq);
> + head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
> + ARRAY_SIZE(vq->iov), &out, &in,
> + NULL, NULL);
> + if (head < 0) {
> + vs->vs_events_dropped = true;
> + goto out;
> + }
> + if (head == vq->num) {
> + if (vhost_enable_notify(&vs->dev, vq))
> + goto again;
Could you code this up using loop, without goto please?
> + vs->vs_events_dropped = true;
> + goto out;
> + }
> +
> + if ((vq->iov[out].iov_len != sizeof(struct virtio_scsi_event))) {
We should avoid making layout assumptions. Please don't.
> + vq_err(vq, "Expecting virtio_scsi_event, got %zu bytes\n",
> + vq->iov[out].iov_len);
> + goto out;
> + }
> +
> + if (vs->vs_events_dropped) {
> + event->event |= VIRTIO_SCSI_T_EVENTS_MISSED;
> + vs->vs_events_dropped = false;
> + }
> +
> + eventp = vq->iov[out].iov_base;
> + ret = __copy_to_user(eventp, event, sizeof(*event));
> + if (!ret)
> + vhost_add_used_and_signal(&vs->dev, vq, head, 0);
> + else
> + pr_err("Faulted on tcm_vhost_send_event\n");
vq_err please, this is guest triggerable.
> +out:
> + mutex_unlock(&vq->mutex);
> +}
> +
> +static void tcm_vhost_evt_work(struct vhost_work *work)
> +{
> + struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
> + vs_event_work);
> + struct tcm_vhost_evt *evt;
> + struct llist_node *llnode;
> +
> + llnode = llist_del_all(&vs->vs_event_list);
> + while (llnode) {
> + evt = llist_entry(llnode, struct tcm_vhost_evt, list);
> + llnode = llist_next(llnode);
> + tcm_vhost_do_evt_work(vs, &evt->event);
> + tcm_vhost_free_evt(evt);
> + }
> +}
> +
> /* Fill in status and signal that we are done processing this command
> *
> * This is scheduled in the vhost work queue so we are called with the
owner
> @@ -757,9 +846,41 @@ static void vhost_scsi_ctl_handle_kick(struct
vhost_work *work)
> pr_debug("%s: The handling func for control queue.\n",
__func__);
> }
>
> +static int tcm_vhost_send_evt(struct vhost_scsi *vs, struct tcm_vhost_tpg
*tpg,
> + struct se_lun *lun, u32 event, u32 reason)
Align ) on ( please.
> +{
> + struct tcm_vhost_evt *evt;
> +
> + if (!vs->vs_endpoint)
> + return -EOPNOTSUPP;
> +
Pls add a comment explaining the abive.
Is this dereference safe without any locking?
> + evt = tcm_vhost_allocate_evt(event, reason);
> + if (!evt)
> + return -ENOMEM;
And what happens then? How about we set event missed flag too?
> +
> + if (tpg && lun) {
> + evt->event.lun[0] = 0x01;
> + evt->event.lun[1] = tpg->tport_tpgt & 0xFF;
> + if (lun->unpacked_lun >= 256)
> + evt->event.lun[2] = lun->unpacked_lun >> 8 | 0x40 ;
> + evt->event.lun[3] = lun->unpacked_lun & 0xFF;
I know it's not your fault but we really should share this code with
virtio scsi. Pls add TODO now.
> + }
> +
> + llist_add(&evt->list, &vs->vs_event_list);
This can queue up quite a bit of memory if the handler thread
is delayed, no? Can we limit the # of outstanding events?
Will guest recover from a missed event?
> + vhost_work_queue(&vs->dev, &vs->vs_event_work);
> +
> + return 0;
> +}
> +
> static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
> {
> - pr_debug("%s: The handling func for event queue.\n", __func__);
> + struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
> + poll.work);
> + struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
> +
> + if (vs->vs_events_dropped)
> + tcm_vhost_send_evt(vs, NULL, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
> +
> }
>
> static void vhost_scsi_handle_kick(struct vhost_work *work)
> @@ -815,6 +936,7 @@ static int vhost_scsi_set_endpoint(
> return -EEXIST;
> }
> tv_tpg->tv_tpg_vhost_count++;
> + tv_tpg->vhost_scsi = vs;
> vs->vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
> smp_mb__after_atomic_inc();
> match = true;
> @@ -875,6 +997,7 @@ static int vhost_scsi_clear_endpoint(
> goto err;
> }
> tv_tpg->tv_tpg_vhost_count--;
> + tv_tpg->vhost_scsi = NULL;
> vs->vs_tpg[target] = NULL;
> vs->vs_endpoint = false;
> }
> @@ -896,6 +1019,7 @@ static int vhost_scsi_open(struct inode *inode, struct
file *f)
> return -ENOMEM;
>
> vhost_work_init(&s->vs_completion_work,
vhost_scsi_complete_cmd_work);
> + vhost_work_init(&s->vs_event_work, tcm_vhost_evt_work);
>
> s->vqs[VHOST_SCSI_VQ_CTL].handle_kick = vhost_scsi_ctl_handle_kick;
> s->vqs[VHOST_SCSI_VQ_EVT].handle_kick = vhost_scsi_evt_handle_kick;
> @@ -941,7 +1065,7 @@ static void vhost_scsi_flush(struct vhost_scsi *vs)
>
> static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
> {
> - if (features & ~VHOST_FEATURES)
> + if (features & ~VHOST_SCSI_FEATURES)
> return -EOPNOTSUPP;
>
> mutex_lock(&vs->dev.mutex);
> @@ -987,7 +1111,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned
int ioctl,
> return -EFAULT;
> return 0;
> case VHOST_GET_FEATURES:
> - features = VHOST_FEATURES;
> + features = VHOST_SCSI_FEATURES;
> if (copy_to_user(featurep, &features, sizeof features))
> return -EFAULT;
> return 0;
> @@ -1057,6 +1181,40 @@ static char *tcm_vhost_dump_proto_id(struct
tcm_vhost_tport *tport)
> return "Unknown";
> }
>
> +static int tcm_vhost_hotplug(struct tcm_vhost_tpg *tpg, struct se_lun
*lun)
> +{
> + struct vhost_scsi *vs = tpg->vhost_scsi;
> + u64 features;
> +
> + if (!vs)
> + return -EOPNOTSUPP;
> +
> + features = vs->dev.acked_features;
> + if (!(features & 1ULL << VIRTIO_SCSI_F_HOTPLUG))
> + return -EOPNOTSUPP;
> +
> + return tcm_vhost_send_evt(vs, tpg, lun,
> + VIRTIO_SCSI_T_TRANSPORT_RESET,
> + VIRTIO_SCSI_EVT_RESET_RESCAN);
> +}
> +
> +static int tcm_vhost_hotunplug(struct tcm_vhost_tpg *tpg, struct se_lun
*lun)
> +{
> + struct vhost_scsi *vs = tpg->vhost_scsi;
> + u64 features;
> +
> + if (!vs)
> + return -EOPNOTSUPP;
> +
What are we checking for here, and why is it safe to do
outside any lock?
> + features = vs->dev.acked_features;
> + if (!(features & 1ULL << VIRTIO_SCSI_F_HOTPLUG))
> + return -EOPNOTSUPP;
> +
> + return tcm_vhost_send_evt(vs, tpg, lun,
> + VIRTIO_SCSI_T_TRANSPORT_RESET,
> + VIRTIO_SCSI_EVT_RESET_REMOVED);
> +}
> +
> static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
> struct se_lun *lun)
> {
> @@ -1067,18 +1225,21 @@ static int tcm_vhost_port_link(struct
se_portal_group *se_tpg,
> tv_tpg->tv_tpg_port_count++;
> mutex_unlock(&tv_tpg->tv_tpg_mutex);
>
> + tcm_vhost_hotplug(tv_tpg, lun);
> +
> return 0;
> }
>
> static void tcm_vhost_port_unlink(struct se_portal_group *se_tpg,
> - struct se_lun *se_lun)
> + struct se_lun *lun)
> {
> struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> struct tcm_vhost_tpg, se_tpg);
> -
> mutex_lock(&tv_tpg->tv_tpg_mutex);
> tv_tpg->tv_tpg_port_count--;
> mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +
> + tcm_vhost_hotunplug(tv_tpg, lun);
> }
>
> static struct se_node_acl *tcm_vhost_make_nodeacl(
> diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
> index 1d2ae7a..191a945 100644
> --- a/drivers/vhost/tcm_vhost.h
> +++ b/drivers/vhost/tcm_vhost.h
> @@ -70,6 +70,8 @@ struct tcm_vhost_tpg {
> struct tcm_vhost_tport *tport;
> /* Returned by tcm_vhost_make_tpg() */
> struct se_portal_group se_tpg;
> + /* Pointer back to struct vhost_scsi*/
> + void *vhost_scsi;
Does it have to be void? Any why?
What lock protects this field? Please add a comment.
> };
>
> struct tcm_vhost_tport {
> @@ -83,6 +85,13 @@ struct tcm_vhost_tport {
> struct se_wwn tport_wwn;
> };
>
> +struct tcm_vhost_evt {
> + /* virtio_scsi event */
> + struct virtio_scsi_event event;
> + /* virtio_scsi event list, serviced from vhost worker thread */
> + struct llist_node list;
> +};
> +
> /*
> * As per request from MST, keep TCM_VHOST related ioctl defines out of
> * linux/vhost.h (user-space) for now..
> --
> 1.8.1.4