On Wed, Apr 24, 2013 at 12:18:33PM +0300, Michael S. Tsirkin wrote:
> On Wed, Apr 24, 2013 at 11:32:23AM +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 delete a LUN in targetcli to hotplug or hotunplug a
> > LUN in guest.
> >
> > Changes in v8:
> > - Use vq->mutex for event
> > - Drop tcm_vhost: Add helper to check if endpoint is setup
> > - Rename vs_events_dropped to vs_events_missed
> > - Init lun[] explicitly
> >
> > Changes in v7:
> > - Add vhost_work_flush for vs->vs_event_work to this series
> >
> > Changes in v6:
> > - Pass tcm_vhost_evt to tcm_vhost_do_evt_work
> >
> > Changes in v5:
> > - Switch to int from u64 to vs_events_nr
> > - Set s->vs_events_dropped flag in tcm_vhost_allocate_evt
> > - Do not nest dev mutex within vq mutex
> > - Use vs_events_lock to protect vs_events_dropped and vs_events_nr
> > - Rebase to target/master
> >
> > Changes in v4:
> > - Drop tcm_vhost_check_endpoint in tcm_vhost_send_evt
> > - Add tcm_vhost_check_endpoint in vhost_scsi_evt_handle_kick
> >
> > Changes in v3:
> > - Separate the bug fix to another thread
> >
> > Changes in v2:
> > - Remove code duplication in tcm_vhost_{hotplug,hotunplug}
> > - Fix racing of vs_events_nr
> > - Add flush fix patch to this series
> >
> > Signed-off-by: Asias He <[email protected]>
> > Reviewed-by: Stefan Hajnoczi <[email protected]>
> > ---
> > drivers/vhost/tcm_vhost.c | 203
> > +++++++++++++++++++++++++++++++++++++++++++++-
> > drivers/vhost/tcm_vhost.h | 10 +++
> > 2 files changed, 209 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> > index 88ebb79..def0c57 100644
> > --- a/drivers/vhost/tcm_vhost.c
> > +++ b/drivers/vhost/tcm_vhost.c
> > @@ -66,11 +66,13 @@ enum {
> > * TODO: debug and remove the workaround.
> > */
> > enum {
> > - VHOST_SCSI_FEATURES = VHOST_FEATURES & (~VIRTIO_RING_F_EVENT_IDX)
> > + VHOST_SCSI_FEATURES = (VHOST_FEATURES & (~VIRTIO_RING_F_EVENT_IDX)) |
> > + (1ULL << VIRTIO_SCSI_F_HOTPLUG)
> > };
> >
> > #define VHOST_SCSI_MAX_TARGET 256
> > #define VHOST_SCSI_MAX_VQ 128
> > +#define VHOST_SCSI_MAX_EVENT 128
> >
> > struct vhost_scsi {
> > /* Protected by vhost_scsi->dev.mutex */
> > @@ -82,6 +84,12 @@ 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_missed; /* any missed events, protected by vq->mutex */
> > + int vs_events_nr; /* num of pending events, protected by vq->mutex */
> > };
> >
> > /* Local pointer to allocated TCM configfs fabric module */
> > @@ -361,6 +369,32 @@ static int tcm_vhost_queue_tm_rsp(struct se_cmd
> > *se_cmd)
> > return 0;
> > }
> >
> > +static void tcm_vhost_free_evt(struct vhost_scsi *vs, struct tcm_vhost_evt
> > *evt)
> > +{
> > + vs->vs_events_nr--;
> > + kfree(evt);
> > +}
> > +
> > +static struct tcm_vhost_evt *tcm_vhost_allocate_evt(struct vhost_scsi *vs,
> > + u32 event, u32 reason)
> > +{
> > + struct tcm_vhost_evt *evt;
> > +
> > + if (vs->vs_events_nr > VHOST_SCSI_MAX_EVENT) {
> > + vs->vs_events_missed = true;
> > + return NULL;
> > + }
> > +
> > + evt = kmalloc(sizeof(*evt), GFP_KERNEL);
> > + if (evt) {
>
> !evt should trigger vq_err I think.
> Please do
> if (!evt) {
> vq_err
> return NULL
> }
>
> this way code below has less nesting.
okay.
> > + evt->event.event = event;
> > + evt->event.reason = reason;
> > + vs->vs_events_nr++;
> > + }
> > +
> > + return evt;
> > +}
> > +
> > static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
> > {
> > struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> > @@ -379,6 +413,74 @@ 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 tcm_vhost_evt *evt)
> > +{
> > + struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT];
> > + struct virtio_scsi_event *event = &evt->event;
> > + struct virtio_scsi_event __user *eventp;
> > + unsigned out, in;
> > + int head, ret;
> > +
> > +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_missed = true;
> > + return;
> > + }
> > + if (head == vq->num) {
> > + if (vhost_enable_notify(&vs->dev, vq))
> > + goto again;
> > + vs->vs_events_missed = true;
> > + return;
> > + }
> > +
> > + if ((vq->iov[out].iov_len != sizeof(struct virtio_scsi_event))) {
> > + vq_err(vq, "Expecting virtio_scsi_event, got %zu bytes\n",
> > + vq->iov[out].iov_len);
> > + vs->vs_events_missed = true;
> > + return;
> > + }
> > +
> > + if (vs->vs_events_missed) {
> > + event->event |= VIRTIO_SCSI_T_EVENTS_MISSED;
> > + vs->vs_events_missed = 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
> > + vq_err(vq, "Faulted on tcm_vhost_send_event\n");
> > +}
> > +
> > +static void tcm_vhost_evt_work(struct vhost_work *work)
> > +{
> > + struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
> > + vs_event_work);
> > + struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT];
> > + struct tcm_vhost_evt *evt;
> > + struct llist_node *llnode;
> > +
> > + mutex_lock(&vq->mutex);
> > + if (!vq->private_data)
> > + goto out;
> > +
>
> Wait a second. Once private data is NULL what will free the events?
> Apparently nothing, so it looks like this leaks memory ...
> Maybe move the private_data check within tcm_vhost_evt
> so that events are dropped?
I moved the check into tcm_vhost_do_evt_work?
>
> Please add WARN_ON(s->vs_events_nr) after flush
> so that we catch such leaks
Let's add that in flush series. The flush is broken anyway.
>
> > + 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);
> > + tcm_vhost_free_evt(vs, evt);
> > + }
> > +out:
> > + mutex_unlock(&vq->mutex);
> > +}
> > +
> > /* 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
> > @@ -789,9 +891,50 @@ 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)
>
> All callers just ignore the return code.
> So make this void please.
tcm_vhost_port_link might want the return code in the future.
> > +{
> > + struct tcm_vhost_evt *evt;
> > +
> > + evt = tcm_vhost_allocate_evt(vs, event, reason);
> > + if (!evt)
> > + return -ENOMEM;
> > +
> > + if (tpg && lun) {
> > + /* TODO: share lun setup code with virtio-scsi.ko */
> > + 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 ;
> > + else
> > + evt->event.lun[2] = 0;
> > + evt->event.lun[3] = lun->unpacked_lun & 0xFF;
> > + evt->event.lun[4] = 0;
> > + evt->event.lun[5] = 0;
> > + evt->event.lun[6] = 0;
> > + evt->event.lun[7] = 0;
> > + }
>
> else
> memset(evt->event.lun, 0, sizeof evt->event.lun)
You want to set them all to zero. Current one is even more cleaner.
> > +
> > + llist_add(&evt->list, &vs->vs_event_list);
> > + 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);
> > +
> > + mutex_lock(&vq->mutex);
> > + if (!vq->private_data)
> > + goto out;
> > +
> > + if (vs->vs_events_missed)
> > + tcm_vhost_send_evt(vs, NULL, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
> > +out:
> > + mutex_unlock(&vq->mutex);
> > }
> >
> > static void vhost_scsi_handle_kick(struct vhost_work *work)
> > @@ -815,6 +958,7 @@ static void vhost_scsi_flush(struct vhost_scsi *vs)
> > 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);
> > }
> >
> > /*
> > @@ -873,6 +1017,7 @@ static int vhost_scsi_set_endpoint(
> > return -EEXIST;
> > }
> > tv_tpg->tv_tpg_vhost_count++;
> > + tv_tpg->vhost_scsi = vs;
> > vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
> > smp_mb__after_atomic_inc();
> > match = true;
> > @@ -956,6 +1101,7 @@ static int vhost_scsi_clear_endpoint(
> > goto err_tpg;
> > }
> > tv_tpg->tv_tpg_vhost_count--;
> > + tv_tpg->vhost_scsi = NULL;
> > vs->vs_tpg[target] = NULL;
> > match = true;
> > mutex_unlock(&tv_tpg->tv_tpg_mutex);
> > @@ -1015,6 +1161,10 @@ 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->vs_events_nr = 0;
> > + s->vs_events_missed = false;
>
> It's unfortunate that vs_events_missed state is lost if
> we close the device and reopen it.
> It should be possible to reattach vhost to a running guest.
> How about, a new ioctl to get and set vs_events_missed?
> This will put userspace in control.
In patch 3/3.
> >
> > 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;
> > @@ -1145,6 +1295,48 @@ static char *tcm_vhost_dump_proto_id(struct
> > tcm_vhost_tport *tport)
> > return "Unknown";
> > }
> >
> > +static int tcm_vhost_do_plug(struct tcm_vhost_tpg *tpg,
> > + struct se_lun *lun, bool plug)
>
> So this should be void too, and same for all callers, since
> eventually status is ignored.
> > +{
> > +
> > + struct vhost_scsi *vs = tpg->vhost_scsi;
> > + struct vhost_virtqueue *vq;
> > + u32 reason;
> > + int ret;
> > +
> > + mutex_lock(&tpg->tv_tpg_mutex);
> > + vs = tpg->vhost_scsi;
> > + mutex_unlock(&tpg->tv_tpg_mutex);
> > + if (!vs)
> > + return -ENODEV;
> > +
>
> What if clear_endpoint and close happen at this
> point? Can vhost_scsi go away so tcm_vhost_check_feature
> references freed memory?
There is no easy way to handle this. Probably, we need the flush
series to fix this.
> > + if (!tcm_vhost_check_feature(vs, VIRTIO_SCSI_F_HOTPLUG))
> > + return -EOPNOTSUPP;
>
> I am nervious about lock read unlock use.
> Probably all right, but I would prefer this:
> mutex_lock(dev->mutex)
> check feature
> mutex_lock(&vq->mutex)
> mutex_unlock(&vq->mutex)
> mutex_unlock(dev->mutex)
>
> so we know feature did not change meanwhile.
It is not necessary. I will leave this.
> > +
> > + if (plug)
> > + reason = VIRTIO_SCSI_EVT_RESET_RESCAN;
> > + else
> > + reason = VIRTIO_SCSI_EVT_RESET_REMOVED;
> > +
> > + vq = &vs->vqs[VHOST_SCSI_VQ_EVT];
> > + mutex_lock(&vq->mutex);
> > + ret = tcm_vhost_send_evt(vs, tpg, lun,
> > + VIRTIO_SCSI_T_TRANSPORT_RESET, reason);
> > + mutex_unlock(&vq->mutex);
> > +
> > + return ret;
> > +}
> > +
> > +static int tcm_vhost_hotplug(struct tcm_vhost_tpg *tpg, struct se_lun *lun)
> > +{
> > + return tcm_vhost_do_plug(tpg, lun, true);
> > +}
> > +
> > +static int tcm_vhost_hotunplug(struct tcm_vhost_tpg *tpg, struct se_lun
> > *lun)
> > +{
> > + return tcm_vhost_do_plug(tpg, lun, false);
> > +}
> > +
> > static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
> > struct se_lun *lun)
> > {
> > @@ -1155,18 +1347,21 @@ 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);
> > -
>
> I like this empty line here, let's keep it around.
> It separates variables from code.
done.
> > 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..94e9ee53 100644
> > --- a/drivers/vhost/tcm_vhost.h
> > +++ b/drivers/vhost/tcm_vhost.h
> > @@ -53,6 +53,7 @@ struct tcm_vhost_nacl {
> > struct se_node_acl se_node_acl;
> > };
> >
> > +struct vhost_scsi;
> > struct tcm_vhost_tpg {
> > /* Vhost port target portal group tag for TCM */
> > u16 tport_tpgt;
> > @@ -70,6 +71,8 @@ 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, protected by tv_tpg_mutex */
>
> Remove the text 'Pointer back to struct vhost_scsi'
> this repeats the type right below it.
> Would prefer a different name as well, e.g.
> vscsi.
I changed to 'Pointer back to vhost_scsi'.
> > + struct vhost_scsi *vhost_scsi;
> > };
> >
> > struct tcm_vhost_tport {
> > @@ -83,6 +86,13 @@ struct tcm_vhost_tport {
> > struct se_wwn tport_wwn;
> > };
> >
> > +struct tcm_vhost_evt {
> > + /* virtio_scsi event */
>
> /* event to be sent to guest */
okay.
> > + struct virtio_scsi_event event;
> > + /* virtio_scsi event list, serviced from vhost worker thread */
>
> /* event list, serviced from vs_event_work handler */
okay.
> > + 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
--
Asias
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