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Date: Thu, 05 Jul 2012 09:24:16 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Cong Meng <mc@...ux.vnet.ibm.com>
CC: stefanha@...ux.vnet.ibm.com, linuxram@...ibm.com,
senwang@...ux.vnet.ibm.com, zwanp@...ibm.com,
virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH v3] virtio-scsi: hotplug support for virtio-scsi
Il 05/07/2012 09:09, 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
> v3: add handle event dropped, and typo fix
>
> Signed-off-by: Sen Wang <senwang@...ux.vnet.ibm.com>
> Signed-off-by: Cong Meng <mc@...ux.vnet.ibm.com>
> ---
> 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..d87446b 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 ready 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);
Coding standard (no parentheses on the right hand side of operators).
Also, you're missing a loop that calls cancel_work_sync in virtscsi_remove.
I believe with these changes we're good to go. Thanks again, and sorry
for missing the cancel_work_sync issue so far.
Paolo
> + 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 +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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