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Message-ID: <CAEH94Liq=F5SWO4HsBbvBy-Yu15ni33qRrL4-4NDgeoqXA+QCQ@mail.gmail.com>
Date:	Wed, 4 Jul 2012 14:10:15 +0800
From:	Zhi Yong Wu <zwu.kernel@...il.com>
To:	Cong Meng <mc@...ux.vnet.ibm.com>
Cc:	Paolo Bonzini <pbonzini@...hat.com>, stefanha@...ux.vnet.ibm.com,
	linux-scsi@...r.kernel.org, senwang@...ux.vnet.ibm.com,
	zwanp@...ibm.com, linuxram@...ibm.com,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v2] virtio-scsi: hotplug support for virtio-scsi

On Tue, Jul 3, 2012 at 1:41 PM, Cong Meng <mc@...ux.vnet.ibm.com> wrote:
> This patch implements the hotplug support for virtio-scsi.
> When there is a device attached/detached, the virtio-scsi driver will be
> signaled via event virtual queue and it will add/remove the scsi device
> in question automatically.
>
> v2: handle no_event event
>
> Signed-off-by: Cong Meng <mc@...ux.vnet.ibm.com>
> Signed-off-by: Sen Wang <senwang@...ux.vnet.ibm.com>
> ---
>  drivers/scsi/virtio_scsi.c  |  113 ++++++++++++++++++++++++++++++++++++++++++-
>  include/linux/virtio_scsi.h |    9 ++++
>  2 files changed, 121 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 9fc5e67..e44b2d6 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -25,6 +25,7 @@
>  #include <scsi/scsi_cmnd.h>
>
>  #define VIRTIO_SCSI_MEMPOOL_SZ 64
> +#define VIRTIO_SCSI_EVENT_LEN 8
>
>  /* Command queue element */
>  struct virtio_scsi_cmd {
> @@ -43,6 +44,12 @@ struct virtio_scsi_cmd {
>         } resp;
>  } ____cacheline_aligned_in_smp;
>
> +struct virtio_scsi_event_node {
> +       struct virtio_scsi *vscsi;
> +       struct virtio_scsi_event event;
> +       struct work_struct work;
> +};
> +
>  struct virtio_scsi_vq {
>         /* Protects vq */
>         spinlock_t vq_lock;
> @@ -67,6 +74,9 @@ struct virtio_scsi {
>         struct virtio_scsi_vq event_vq;
>         struct virtio_scsi_vq req_vq;
>
> +       /* Get some buffers reday for event vq */
s/reday/ready/   ^^^^
> +       struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN];
> +
>         struct virtio_scsi_target_state *tgt[];
>  };
>
> @@ -202,6 +212,97 @@ static void virtscsi_ctrl_done(struct virtqueue *vq)
>         spin_unlock_irqrestore(&vscsi->ctrl_vq.vq_lock, flags);
>  };
>
> +static int virtscsi_kick_event(struct virtio_scsi *vscsi,
> +                              struct virtio_scsi_event_node *event_node)
> +{
> +       int ret;
> +       struct scatterlist sg;
> +       unsigned long flags;
> +
> +       sg_set_buf(&sg, &event_node->event, sizeof(struct virtio_scsi_event));
> +
> +       spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags);
> +
> +       ret = virtqueue_add_buf(vscsi->event_vq.vq, &sg, 0, 1, event_node, GFP_ATOMIC);
> +       if (ret >= 0)
> +               virtqueue_kick(vscsi->event_vq.vq);
> +
> +       spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags);
> +
> +       return ret;
> +}
> +
> +static int virtscsi_kick_event_all(struct virtio_scsi *vscsi)
> +{
> +       int i;
> +
> +       for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++) {
> +               vscsi->event_list[i].vscsi = vscsi;
> +               virtscsi_kick_event(vscsi, &vscsi->event_list[i]);
> +       }
> +
> +       return 0;
> +}
> +
> +static void virtscsi_handle_transport_reset(struct virtio_scsi *vscsi,
> +                                            struct virtio_scsi_event *event)
> +{
> +       struct scsi_device *sdev;
> +       struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
> +       unsigned int target = event->lun[1];
> +       unsigned int lun = (event->lun[2] << 8) | event->lun[3];
> +
> +       switch (event->reason) {
> +       case VIRTIO_SCSI_EVT_RESET_RESCAN:
> +               scsi_add_device(shost, 0, target, lun);
> +               break;
> +       case VIRTIO_SCSI_EVT_RESET_REMOVED:
> +               sdev = scsi_device_lookup(shost, 0, target, lun);
> +               if (sdev) {
> +                       scsi_remove_device(sdev);
> +                       scsi_device_put(sdev);
> +               } else {
> +                       pr_err("SCSI device %d 0 %d %d not found\n",
> +                               shost->host_no, target, lun);
> +               }
> +               break;
> +       default:
> +               pr_info("Unsupport virtio scsi event reason %x\n", event->reason);
> +       }
> +}
> +
> +static void virtscsi_handle_event(struct work_struct *work)
> +{
> +       struct virtio_scsi_event_node *event_node =
> +               container_of(work, struct virtio_scsi_event_node, work);
> +       struct virtio_scsi *vscsi = event_node->vscsi;
> +       struct virtio_scsi_event *event = &event_node->event;
> +
> +       if (event->event & VIRTIO_SCSI_T_EVENTS_MISSED) {
> +               event->event &= (~VIRTIO_SCSI_T_EVENTS_MISSED);
> +               /* FIXME: handle event missed here */
> +       }
> +
> +       switch (event->event) {
> +       case VIRTIO_SCSI_T_NO_EVENT:
> +               break;
> +       case VIRTIO_SCSI_T_TRANSPORT_RESET:
> +               virtscsi_handle_transport_reset(vscsi, event);
> +               break;
> +       default:
> +               pr_err("Unsupport virtio scsi event %x\n", event->event);
> +       }
> +       virtscsi_kick_event(vscsi, event_node);
> +}
> +
> +static void virtscsi_complete_event(void *buf)
> +{
> +       struct virtio_scsi_event_node *event_node = buf;
> +
> +       INIT_WORK(&event_node->work, virtscsi_handle_event);
> +       schedule_work(&event_node->work);
> +}
> +
>  static void virtscsi_event_done(struct virtqueue *vq)
>  {
>         struct Scsi_Host *sh = virtio_scsi_host(vq->vdev);
> @@ -209,7 +310,7 @@ static void virtscsi_event_done(struct virtqueue *vq)
>         unsigned long flags;
>
>         spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags);
> -       virtscsi_vq_done(vq, virtscsi_complete_free);
> +       virtscsi_vq_done(vq, virtscsi_complete_event);
>         spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags);
>  };
>
> @@ -510,6 +611,10 @@ static int virtscsi_init(struct virtio_device *vdev,
>         virtscsi_config_set(vdev, cdb_size, VIRTIO_SCSI_CDB_SIZE);
>         virtscsi_config_set(vdev, sense_size, VIRTIO_SCSI_SENSE_SIZE);
>
> +       if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
> +               virtscsi_kick_event_all(vscsi);
> +       }
> +
>         /* We need to know how many segments before we allocate.  */
>         sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1;
>
> @@ -608,7 +713,13 @@ static struct virtio_device_id id_table[] = {
>         { 0 },
>  };
>
> +static unsigned int features[] = {
> +       VIRTIO_SCSI_F_HOTPLUG
> +};
> +
>  static struct virtio_driver virtio_scsi_driver = {
> +       .feature_table = features,
> +       .feature_table_size = ARRAY_SIZE(features),
>         .driver.name = KBUILD_MODNAME,
>         .driver.owner = THIS_MODULE,
>         .id_table = id_table,
> diff --git a/include/linux/virtio_scsi.h b/include/linux/virtio_scsi.h
> index 8ddeafd..dc8d305 100644
> --- a/include/linux/virtio_scsi.h
> +++ b/include/linux/virtio_scsi.h
> @@ -69,6 +69,10 @@ struct virtio_scsi_config {
>         u32 max_lun;
>  } __packed;
>
> +/* Feature Bits */
> +#define VIRTIO_SCSI_F_INOUT                    0
> +#define VIRTIO_SCSI_F_HOTPLUG                  1
> +
>  /* Response codes */
>  #define VIRTIO_SCSI_S_OK                       0
>  #define VIRTIO_SCSI_S_OVERRUN                  1
> @@ -105,6 +109,11 @@ struct virtio_scsi_config {
>  #define VIRTIO_SCSI_T_TRANSPORT_RESET          1
>  #define VIRTIO_SCSI_T_ASYNC_NOTIFY             2
>
> +/* Reasons of transport reset event */
> +#define VIRTIO_SCSI_EVT_RESET_HARD             0
> +#define VIRTIO_SCSI_EVT_RESET_RESCAN           1
> +#define VIRTIO_SCSI_EVT_RESET_REMOVED          2
> +
>  #define VIRTIO_SCSI_S_SIMPLE                   0
>  #define VIRTIO_SCSI_S_ORDERED                  1
>  #define VIRTIO_SCSI_S_HEAD                     2
> --
> 1.7.7.6
>
> _______________________________________________
> Virtualization mailing list
> Virtualization@...ts.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/virtualization



-- 
Regards,

Zhi Yong Wu
--
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