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Message-ID: <20120702032057.Horde.WOVSk5ir309P8UvZ8oq3rUA@imap.linux.ibm.com>
Date: Mon, 02 Jul 2012 03:20:57 -0400
From: mc@...ux.vnet.ibm.com
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: Rusty Russell <rusty@...tcorp.com.au>,
"Nicholas A. Bellinger" <nab@...ux-iscsi.org>,
stefanha@...ux.vnet.ibm.com, linuxram@...ibm.com,
Anthony Liguori <anthony@...emonkey.ws>,
senwang@...ux.vnet.ibm.com, zwanp@...ibm.com,
"James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH] virtio-scsi: hotplug suppot for virtio-scsi
Quoting Paolo Bonzini <pbonzini@...hat.com>:
> 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@...ux.vnet.ibm.com>
>> Signed-off-by: Sen Wang <senwang@...ux.vnet.ibm.com>
>
> 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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