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

mc@xxxxxxxxxxxxxxxxxx · Wed, 04 Jul 2012 04:11:24 -0400

Quoting Paolo Bonzini <pbonzini@xxxxxxxxxx>:

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@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sen Wang <senwang@xxxxxxxxxxxxxxxxxx>

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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