[PATCH v4 2/3] scsi: core: Support disabling fair tag sharing
From: Bart Van Assche <bvanassche@acm.org>
Date: 2023-10-23 20:36:59
Also in:
linux-scsi
Subsystem:
scsi subsystem, the rest · Maintainers:
"James E.J. Bottomley", "Martin K. Petersen", Linus Torvalds
Allow SCSI drivers to disable the block layer fair tag sharing algorithm. Cc: Christoph Hellwig <hch@lst.de> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Ming Lei <redacted> Cc: Keith Busch <kbusch@kernel.org> Cc: Damien Le Moal <redacted> Cc: Yu Kuai <redacted> Cc: Ed Tsai <redacted> Signed-off-by: Bart Van Assche <bvanassche@acm.org> --- drivers/scsi/hosts.c | 1 + drivers/scsi/scsi_lib.c | 2 ++ include/scsi/scsi_host.h | 6 ++++++ 3 files changed, 9 insertions(+)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index d7f51b84f3c7..872f87001374 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c@@ -442,6 +442,7 @@ struct Scsi_Host *scsi_host_alloc(const struct scsi_host_template *sht, int priv shost->no_write_same = sht->no_write_same; shost->host_tagset = sht->host_tagset; shost->queuecommand_may_block = sht->queuecommand_may_block; + shost->disable_fair_tag_sharing = sht->disable_fair_tag_sharing; if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler) shost->eh_deadline = -1;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index c2f647a7c1b0..68683988c466 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c@@ -1985,6 +1985,8 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy); if (shost->queuecommand_may_block) tag_set->flags |= BLK_MQ_F_BLOCKING; + if (shost->disable_fair_tag_sharing) + tag_set->flags |= BLK_MQ_F_DISABLE_FAIR_TAG_SHARING; tag_set->driver_data = shost; if (shost->host_tagset) tag_set->flags |= BLK_MQ_F_TAG_HCTX_SHARED;
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 49f768d0ff37..2cd8a41b1f1c 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h@@ -461,6 +461,9 @@ struct scsi_host_template { /* The queuecommand callback may block. See also BLK_MQ_F_BLOCKING. */ unsigned queuecommand_may_block:1; + /* See also BLK_MQ_F_DISABLE_FAIR_TAG_SHARING. */ + unsigned disable_fair_tag_sharing:1; + /* * Countdown for host blocking with no commands outstanding. */
@@ -659,6 +662,9 @@ struct Scsi_Host { /* The queuecommand callback may block. See also BLK_MQ_F_BLOCKING. */ unsigned queuecommand_may_block:1; + /* See also BLK_MQ_F_DISABLE_FAIR_TAG_SHARING. */ + unsigned disable_fair_tag_sharing:1; + /* Host responded with short (<36 bytes) INQUIRY result */ unsigned short_inquiry:1;