IB/srp: adjust can_queue

Makes sure that the SCSI mid-layer never tries to queue more than (SRP request limit) - 1 SCSI commands. Improves performance for targets whose request limit is less than or equal to SRP_SQ_REQ_SIZE (63) by reducing the number of BUSY responses.

---
 drivers/infiniband/ulp/srp/ib_srp.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index 1c40ac3..4efda6c 100644
@@ -1436,7 +1436,7 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
 			target->max_ti_iu_len = be32_to_cpu(rsp->max_ti_iu_len);
 			target->req_lim       = be32_to_cpu(rsp->req_lim_delta);
 
-			target->scsi_host->can_queue = min(target->req_lim,
+			target->scsi_host->can_queue = min(target->req_lim - 1,
 							   target->scsi_host->can_queue);
 		} else {
 			shost_printk(KERN_WARNING, target->scsi_host,

1.6.4.2

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This is a better commit message, but why is it important to be less than SRP_REQ_SQ_SIZE or (SRP request limit) - 1 commands?

You and I know that it is because we reserve one credit for sending task management requests, but will future readers?

On that topic, I wonder if we should have a comment there, since we'll otherwise have a magic number.

Dave
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