On Fri, 2019-01-18 at 10:48 -0700, Jens Axboe wrote:
> It's UFS that totally buggy, if you look at its queuecommand, it does:
>
> if (!down_read_trylock(&hba->clk_scaling_lock))
>
> return SCSI_MLQUEUE_HOST_BUSY;
>
> UFS either needs to get fixed up, or we'll want a way to do something like
> the below.
>
> Marc, can you test this?
>
>
> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
> index eaf329db3973..e28c3420a9d9 100644
> --- a/drivers/scsi/hosts.c
> +++ b/drivers/scsi/hosts.c
> @@ -412,6 +412,7 @@ struct Scsi_Host *scsi_host_alloc(struct
> scsi_host_template *sht, int privsize)
> shost->hostt = sht;
> shost->this_id = sht->this_id;
> shost->can_queue = sht->can_queue;
> + shost->queue_may_block = sht->queue_may_block;
> shost->sg_tablesize = sht->sg_tablesize;
> shost->sg_prot_tablesize = sht->sg_prot_tablesize;
> shost->cmd_per_lun = sht->cmd_per_lun;
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index b13cc9288ba0..4e266af2871f 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -1902,6 +1902,8 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
> shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
> shost->tag_set.flags |=
> BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
> + if (shost->queue_may_blocK)
> + shost->tag_set.flags |= BLK_MQ_F_BLOCKING;
> shost->tag_set.driver_data = shost;
>
> return blk_mq_alloc_tag_set(&shost->tag_set);
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 9ba7671b84f8..9ab354e43630 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -6981,6 +6981,7 @@ static struct scsi_host_template ufshcd_driver_template
> = {
> .sg_tablesize = SG_ALL,
> .cmd_per_lun = UFSHCD_CMD_PER_LUN,
> .can_queue = UFSHCD_CAN_QUEUE,
> + .queue_may_block = 1,
> .max_host_blocked = 1,
> .track_queue_depth = 1,
> .sdev_groups = ufshcd_driver_groups,
> diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
> index 6ca954e9f752..30aa7b6c4342 100644
> --- a/include/scsi/scsi_host.h
> +++ b/include/scsi/scsi_host.h
> @@ -339,6 +339,11 @@ struct scsi_host_template {
> */
> int can_queue;
>
> + /*
> + * If the ->queuecommand() ever blocks, this should be set
> + */
> + int queue_may_block;
> +
> /*
> * In many instances, especially where disconnect / reconnect are
> * supported, our host also has an ID on the SCSI bus. If this is
> @@ -584,6 +589,7 @@ struct Scsi_Host {
>
> int this_id;
> int can_queue;
> + int queue_may_block;
> short cmd_per_lun;
> short unsigned int sg_tablesize;
> short unsigned int sg_prot_tablesize;
Hi Jens,
Did you perhaps want to include a change from down_read_trylock() into
down_read() in the UFS queuecommand function in this patch?
Thanks,
Bart.
