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    SubjectRe: [PATCH v2] virtio-scsi: hotplug support for virtio-scsi

    Quoting Paolo Bonzini <pbonzini@redhat.com>:

    > Il 03/07/2012 07:41, Cong Meng ha scritto:
    >> 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@linux.vnet.ibm.com>
    >> Signed-off-by: Sen Wang <senwang@linux.vnet.ibm.com>
    >
    > The SoB lines are swapped. Otherwise looks good. Since you have to
    > respin, please add dropped event support too, it shouldn't be hard.

    What does "The SoB lines are swapped" mean? should the changelog be
    placed after SoB lines?

    >
    > Paolo
    >
    >> ---
    >> 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 */
    >> + 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
    >>





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