Re: [PATCH 09/30] scsi: kill off the legacy IO path

Omar Sandoval
2018-11-01T21:11:56Z

On Wed, Oct 31, 2018 at 11:59:01AM -0600, Jens Axboe wrote:
> Cc: linux-scsi@vger.kernel.org
> Acked-by: Himanshu Madhani <himanshu.madhani@cavium.com>
> Reviewed-by: Hannes Reinecke <hare@suse.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>

A bunch of really trivial nitpicks below, only to prove that I read the
thing ;)

Reviewed-by: Omar Sandoval <osandov@fb.com>

> ---
> Documentation/scsi/scsi-parameters.txt | 5 -
> drivers/scsi/Kconfig | 12 -
> drivers/scsi/cxlflash/main.c | 6 -
> drivers/scsi/hosts.c | 29 +-
> drivers/scsi/lpfc/lpfc_scsi.c | 2 +-
> drivers/scsi/qedi/qedi_main.c | 3 +-
> drivers/scsi/qla2xxx/qla_os.c | 30 +-
> drivers/scsi/scsi.c | 5 +-
> drivers/scsi/scsi_debug.c | 3 +-
> drivers/scsi/scsi_error.c | 2 +-
> drivers/scsi/scsi_lib.c | 603 ++-----------------------
> drivers/scsi/scsi_priv.h | 1 -
> drivers/scsi/scsi_scan.c | 10 +-
> drivers/scsi/scsi_sysfs.c | 8 +-
> drivers/scsi/ufs/ufshcd.c | 6 -
> include/scsi/scsi_host.h | 18 +-
> include/scsi/scsi_tcq.h | 14 +-
> 17 files changed, 77 insertions(+), 680 deletions(-)

> diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
> index 8794e54f43a9..3e2665c66bc4 100644
> --- a/drivers/scsi/qla2xxx/qla_os.c
> +++ b/drivers/scsi/qla2xxx/qla_os.c
> @@ -857,13 +857,9 @@ qla2xxx_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
> }
>
> if (ha->mqenable) {
> - if (shost_use_blk_mq(vha->host)) {
> - tag = blk_mq_unique_tag(cmd->request);
> - hwq = blk_mq_unique_tag_to_hwq(tag);
> - qpair = ha->queue_pair_map[hwq];
> - } else if (vha->vp_idx && vha->qpair) {
> - qpair = vha->qpair;
> - }
> + tag = blk_mq_unique_tag(cmd->request);
> + hwq = blk_mq_unique_tag_to_hwq(tag);
> + qpair = ha->queue_pair_map[hwq];
>
> if (qpair)
> return qla2xxx_mqueuecommand(host, cmd, qpair);
> @@ -3153,7 +3149,7 @@ qla2x00_probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
> goto probe_failed;
> }
>
> - if (ha->mqenable && shost_use_blk_mq(host)) {
> + if (ha->mqenable) {
> /* number of hardware queues supported by blk/scsi-mq*/
> host->nr_hw_queues = ha->max_qpairs;
>
> @@ -3265,25 +3261,17 @@ qla2x00_probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
> base_vha->mgmt_svr_loop_id, host->sg_tablesize);
>
> if (ha->mqenable) {
> - bool mq = false;
> bool startit = false;
>
> - if (QLA_TGT_MODE_ENABLED()) {
> - mq = true;
> + if (QLA_TGT_MODE_ENABLED())
> startit = false;
> - }
>
> - if ((ql2x_ini_mode == QLA2XXX_INI_MODE_ENABLED) &&
> - shost_use_blk_mq(host)) {
> - mq = true;
> + if (ql2x_ini_mode == QLA2XXX_INI_MODE_ENABLED)
> startit = true;
> - }

This could just be

startit = (QLA_TGT_MODE_ENABLED() ||
(ql2x_ini_mode == QLA2XXX_INI_MODE_ENABLED));

>
> - if (mq) {
> - /* Create start of day qpairs for Block MQ */
> - for (i = 0; i < ha->max_qpairs; i++)
> - qla2xxx_create_qpair(base_vha, 5, 0, startit);
> - }
> + /* Create start of day qpairs for Block MQ */
> + for (i = 0; i < ha->max_qpairs; i++)
> + qla2xxx_create_qpair(base_vha, 5, 0, startit);
> }
>
> if (ha->flags.running_gold_fw)
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> index fc1356d101b0..99db3f4316b5 100644
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -780,11 +780,8 @@ MODULE_LICENSE("GPL");
> module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
> MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
>
> -#ifdef CONFIG_SCSI_MQ_DEFAULT
> +/* Kill module parameter */

Is this a leftover todo comment for yourself, or a note for the future?
If the latter, I think it could be clearer.

> bool scsi_use_blk_mq = true;
> -#else
> -bool scsi_use_blk_mq = false;
> -#endif
> module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR | S_IRUGO);
>
> static int __init init_scsi(void)
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index 60bcc6df97a9..4740f1e9dd17 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -5881,8 +5881,7 @@ static int sdebug_driver_probe(struct device *dev)
> }
> /* Decide whether to tell scsi subsystem that we want mq */
> /* Following should give the same answer for each host */
> - if (shost_use_blk_mq(hpnt))
> - hpnt->nr_hw_queues = submit_queues;
> + hpnt->nr_hw_queues = submit_queues;
>
> sdbg_host->shost = hpnt;
> *((struct sdebug_host_info **)hpnt->hostdata) = sdbg_host;
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index c736d61b1648..fff128aa9ec2 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -308,7 +308,7 @@ enum blk_eh_timer_return scsi_times_out(struct request *req)
> * error handler. In that case we can return immediately as no
> * further action is required.
> */
> - if (req->q->mq_ops && !blk_mq_mark_complete(req))
> + if (!blk_mq_mark_complete(req))
> return rtn;
> if (scsi_abort_command(scmd) != SUCCESS) {
> set_host_byte(scmd, DID_TIME_OUT);
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 8b0345924a92..651be30ba96a 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c

> @@ -687,37 +601,22 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
> destroy_rcu_head(&cmd->rcu);
> }
>
> - if (req->mq_ctx) {
> - /*
> - * In the MQ case the command gets freed by __blk_mq_end_request,
> - * so we have to do all cleanup that depends on it earlier.
> - *
> - * We also can't kick the queues from irq context, so we
> - * will have to defer it to a workqueue.
> - */
> - scsi_mq_uninit_cmd(cmd);
> -
> - __blk_mq_end_request(req, error);
> -
> - if (scsi_target(sdev)->single_lun ||
> - !list_empty(&sdev->host->starved_list))
> - kblockd_schedule_work(&sdev->requeue_work);
> - else
> - blk_mq_run_hw_queues(q, true);
> - } else {
> - unsigned long flags;
> -
> - if (bidi_bytes)
> - scsi_release_bidi_buffers(cmd);
> - scsi_release_buffers(cmd);
> - scsi_put_command(cmd);
> + /*
> + * In the MQ case the command gets freed by __blk_mq_end_request,
> + * so we have to do all cleanup that depends on it earlier.
> + *
> + * We also can't kick the queues from irq context, so we
> + * will have to defer it to a workqueue.
> + */

This comment is slightly stale, since everything is the MQ case now.

> + scsi_mq_uninit_cmd(cmd);
>
> - spin_lock_irqsave(q->queue_lock, flags);
> - blk_finish_request(req, error);
> - spin_unlock_irqrestore(q->queue_lock, flags);
> + __blk_mq_end_request(req, error);
>
> - scsi_run_queue(q);
> - }
> + if (scsi_target(sdev)->single_lun ||
> + !list_empty(&sdev->host->starved_list))
> + kblockd_schedule_work(&sdev->requeue_work);
> + else
> + blk_mq_run_hw_queues(q, true);
>
> put_device(&sdev->sdev_gendev);
> return false;

> diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
> index 99f1db5e467e..5f21547b2ad2 100644
> --- a/drivers/scsi/scsi_priv.h
> +++ b/drivers/scsi/scsi_priv.h
> @@ -92,7 +92,6 @@ extern void scsi_queue_insert(struct scsi_cmnd *cmd, int reason);
> extern void scsi_io_completion(struct scsi_cmnd *, unsigned int);
> extern void scsi_run_host_queues(struct Scsi_Host *shost);
> extern void scsi_requeue_run_queue(struct work_struct *work);
> -extern struct request_queue *scsi_old_alloc_queue(struct scsi_device *sdev);
> extern struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev);
> extern void scsi_start_queue(struct scsi_device *sdev);
> extern int scsi_mq_setup_tags(struct Scsi_Host *shost);
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 78ca63dfba4a..dd0d516f65e2 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -266,10 +266,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
> */
> sdev->borken = 1;
>
> - if (shost_use_blk_mq(shost))
> - sdev->request_queue = scsi_mq_alloc_queue(sdev);
> - else
> - sdev->request_queue = scsi_old_alloc_queue(sdev);
> + sdev->request_queue = scsi_mq_alloc_queue(sdev);
> if (!sdev->request_queue) {
> /* release fn is set up in scsi_sysfs_device_initialise, so
> * have to free and put manually here */
> @@ -280,11 +277,6 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
> WARN_ON_ONCE(!blk_get_queue(sdev->request_queue));
> sdev->request_queue->queuedata = sdev;
>
> - if (!shost_use_blk_mq(sdev->host)) {
> - blk_queue_init_tags(sdev->request_queue,
> - sdev->host->cmd_per_lun, shost->bqt,
> - shost->hostt->tag_alloc_policy);
> - }
> scsi_change_queue_depth(sdev, sdev->host->cmd_per_lun ?
> sdev->host->cmd_per_lun : 1);
>
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 3aee9464a7bf..12e2c2829df2 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -367,7 +367,6 @@ store_shost_eh_deadline(struct device *dev, struct device_attribute *attr,
>
> static DEVICE_ATTR(eh_deadline, S_IRUGO | S_IWUSR, show_shost_eh_deadline, store_shost_eh_deadline);
>
> -shost_rd_attr(use_blk_mq, "%d\n");
> shost_rd_attr(unique_id, "%u\n");
> shost_rd_attr(cmd_per_lun, "%hd\n");
> shost_rd_attr(can_queue, "%hd\n");
> @@ -386,6 +385,13 @@ show_host_busy(struct device *dev, struct device_attribute *attr, char *buf)
> }
> static DEVICE_ATTR(host_busy, S_IRUGO, show_host_busy, NULL);
>
> +static ssize_t
> +show_use_blk_mq(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + return snprintf(buf, 20, "1\n");
> +}

Looks like you forgot to change this to sprintf()