Skip to content

Commit

Permalink
[SCSI] virtio-scsi: hotplug support for virtio-scsi
Browse files Browse the repository at this point in the history 
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.

Signed-off-by: Sen Wang <senwang@linux.vnet.ibm.com>
Signed-off-by: Cong Meng <mc@linux.vnet.ibm.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
  • Loading branch information
Cong Meng authored and James Bottomley committed Jul 20, 2012
1 parent 2bd37f0 commit 365a715
Show file tree
Hide file tree
Showing 2 changed files with 132 additions and 1 deletion.
124 changes: 123 additions & 1 deletion drivers/scsi/virtio_scsi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 {
Expand All @@ -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;
Expand All @@ -67,6 +74,9 @@ struct virtio_scsi {
struct virtio_scsi_vq event_vq;
struct virtio_scsi_vq req_vq;

/* Get some buffers ready for event vq */
struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN];

struct virtio_scsi_target_state *tgt[];
};

Expand Down Expand Up @@ -202,14 +212,113 @@ 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_cancel_event_work(struct virtio_scsi *vscsi)
{
int i;

for (i = 0; i < VIRTIO_SCSI_EVENT_LEN; i++)
cancel_work_sync(&vscsi->event_list[i].work);
}

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;
scsi_scan_host(virtio_scsi_host(vscsi->vdev));
}

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);
struct virtio_scsi *vscsi = shost_priv(sh);
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);
};

Expand Down Expand Up @@ -510,6 +619,9 @@ 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;

Expand Down Expand Up @@ -580,6 +692,10 @@ static int __devinit virtscsi_probe(struct virtio_device *vdev)
static void __devexit virtscsi_remove(struct virtio_device *vdev)
{
struct Scsi_Host *shost = virtio_scsi_host(vdev);
struct virtio_scsi *vscsi = shost_priv(shost);

if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
virtscsi_cancel_event_work(vscsi);

scsi_remove_host(shost);

Expand Down Expand Up @@ -608,7 +724,13 @@ 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,
Expand Down
9 changes: 9 additions & 0 deletions include/linux/virtio_scsi.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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
Expand Down

0 comments on commit 365a715

Please sign in to comment.