Re: [PATCH] virtio-scsi: hotplug suppot for virtio-scsi
From: mc
Date: Mon Jul 02 2012 - 03:21:03 EST
Quoting Paolo Bonzini <pbonzini@xxxxxxxxxx>:
Il 20/06/2012 08:55, 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.
Signed-off-by: Cong Meng <mc@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sen Wang <senwang@xxxxxxxxxxxxxxxxxx>
Looks good (with one nit below), but please rebase over the four patches
at http://permalink.gmane.org/gmane.linux.kernel/1312496
---
drivers/scsi/virtio_scsi.c | 109
++++++++++++++++++++++++++++++++++++++++++-
include/linux/virtio_scsi.h | 9 ++++
2 files changed, 116 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 1b38431..6dad625 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 {
@@ -43,9 +44,15 @@ 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;
+};
+
/* Driver instance state */
struct virtio_scsi {
- /* Protects ctrl_vq, req_vq and sg[] */
+ /* Protects ctrl_vq, event_vq, req_vq and sg[] */
spinlock_t vq_lock;
struct virtio_device *vdev;
@@ -53,6 +60,9 @@ struct virtio_scsi {
struct virtqueue *event_vq;
struct virtqueue *req_vq;
+ /* Get some buffers reday for event vq */
+ struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN];
+
/* For sglist construction when adding commands to the virtqueue. */
struct scatterlist sg[];
};
@@ -184,9 +194,93 @@ static void virtscsi_ctrl_done(struct virtqueue *vq)
virtscsi_vq_done(vq, virtscsi_complete_free);
};
+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->vq_lock, flags);
+
+ ret = virtqueue_add_buf(vscsi->event_vq, &sg, 0, 1, event_node,
GFP_ATOMIC);
+ if (ret >= 0)
+ virtqueue_kick(vscsi->event_vq);
+
+ spin_unlock_irqrestore(&vscsi->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;
+
+ switch (event->event) {
+ case VIRTIO_SCSI_T_TRANSPORT_RESET:
+ virtscsi_handle_transport_reset(vscsi, event);
+ break;
Please handle VIRTIO_SCSI_T_NO_EVENT too here, and mask out
VIRTIO_SCSI_T_EVENTS_MISSED even if you do not handle it by triggering a
full rescan.
Paolo, what's the appropriate action to response VIRTIO_SCSI_T_NO_EVENT
event? An error message?
I also have some confusion on VIRTIO_SCSI_T_EVENTS_MISSED:
Should VIRTIO_SCSI_T_EVENTS_MISSED always be used with other event flag?
For instanse:
(VIRTIO_SCSI_T_EVENTS_MISSED|VIRTIO_SCSI_T_TRANSPORT_RESET) is used to report
hotplug event dropped when a buffer available.
Thanks.
Cong.
Paolo
+ 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)
{
- virtscsi_vq_done(vq, virtscsi_complete_free);
+ virtscsi_vq_done(vq, virtscsi_complete_event);
};
static void virtscsi_map_sgl(struct scatterlist *sg, unsigned int *p_idx,
@@ -435,6 +529,11 @@ 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);
+ }
+
return 0;
}
@@ -532,7 +631,13 @@ 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
Thanks,
Paolo
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