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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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