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Commit 365a7150 authored by Cong Meng's avatar Cong Meng Committed by James Bottomley
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[SCSI] virtio-scsi: hotplug support for virtio-scsi 



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: default avatarSen Wang <senwang@linux.vnet.ibm.com>
Signed-off-by: default avatarCong Meng <mc@linux.vnet.ibm.com>
Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent 2bd37f0f

drivers/scsi/virtio_scsi.c

+123 −1
Original line number Diff line number Diff line
@@ -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 ready for event vq */

	struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN];



	struct virtio_scsi_target_state *tgt[];

};
@@ -202,6 +212,105 @@ 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);
@@ -209,7 +318,7 @@ 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 +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;
@@ -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);
@@ -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,

include/linux/virtio_scsi.h

+9 −0
Original line number Diff line number Diff line
@@ -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