diff mbox series

[RFC,v3,09/19] scsi: core: increase/decrease target_busy without check can_queue

Message ID 20250314012927.150860-10-jiangjianjun3@huawei.com (mailing list archive)
State New
Headers show
Series scsi: scsi_error: Introduce new error handle mechanism | expand

Commit Message

JiangJianJun March 14, 2025, 1:29 a.m. UTC 
From: Wenchao Hao <haowenchao2@huawei.com>

This is preparation for a genernal target based error handle strategy
to check if to wake up actual error handler.

Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
---
 drivers/scsi/scsi_lib.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

Comments

Bart Van Assche March 14, 2025, 1:35 a.m. UTC | #1 
On 3/13/25 6:29 PM, JiangJianJun wrote:
> This is preparation for a genernal target based error handle strategy
> to check if to wake up actual error handler.

I don't like this change because it slows down the hot path for LLD
drivers that do not set starget->can_queue. Why is this change
necessary? What are the alternatives?

Thanks,

Bart.
diff mbox series

Patch

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 8cdab7ac5980..e477c5d3c393 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -394,8 +394,7 @@  void scsi_device_unbusy(struct scsi_device *sdev, struct scsi_cmnd *cmd)
 
 	scsi_dec_host_busy(shost, cmd);
 
-	if (starget->can_queue > 0)
-		atomic_dec(&starget->target_busy);
+	atomic_dec(&starget->target_busy);
 
 	sbitmap_put(&sdev->budget_map, cmd->budget_token);
 	cmd->budget_token = -1;
@@ -1413,10 +1412,10 @@  static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
 		spin_unlock_irq(shost->host_lock);
 	}
 
+	busy = atomic_inc_return(&starget->target_busy) - 1;
 	if (starget->can_queue <= 0)
 		return 1;
 
-	busy = atomic_inc_return(&starget->target_busy) - 1;
 	if (atomic_read(&starget->target_blocked) > 0) {
 		if (busy)
 			goto starved;
@@ -1441,8 +1440,7 @@  static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
 	list_move_tail(&sdev->starved_entry, &shost->starved_list);
 	spin_unlock_irq(shost->host_lock);
 out_dec:
-	if (starget->can_queue > 0)
-		atomic_dec(&starget->target_busy);
+	atomic_dec(&starget->target_busy);
 	return 0;
 }
 
@@ -1886,8 +1884,7 @@  static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
 out_dec_host_busy:
 	scsi_dec_host_busy(shost, cmd);
 out_dec_target_busy:
-	if (scsi_target(sdev)->can_queue > 0)
-		atomic_dec(&scsi_target(sdev)->target_busy);
+	atomic_dec(&scsi_target(sdev)->target_busy);
 out_put_budget:
 	scsi_mq_put_budget(q, cmd->budget_token);
 	cmd->budget_token = -1;