scsi: lpfc: Update lpfc_ramp_down_queue_handler() logic

scsi: lpfc: Update lpfc_ramp_down_queue_handler() logic

Typically when an out of resource CQE status is detected, the
lpfc_ramp_down_queue_handler() logic is called to help reduce I/O load by
reducing an sdev's queue_depth.

However, the current lpfc_rampdown_queue_depth() logic does not help reduce
queue_depth.  num_cmd_success is never updated and is always zero, which
means new_queue_depth will always be set to sdev->queue_depth.  So,
new_queue_depth = sdev->queue_depth - new_queue_depth always sets
new_queue_depth to zero.  And, scsi_change_queue_depth(sdev, 0) is
essentially a no-op.

Change the lpfc_ramp_down_queue_handler() logic to set new_queue_depth
equal to sdev->queue_depth subtracted from number of times num_rsrc_err was
incremented.  If num_rsrc_err is >= sdev->queue_depth, then set
new_queue_depth equal to 1.  Eventually, the frequency of Good_Status
frames will signal SCSI upper layer to auto increase the queue_depth back
to the driver default of 64 via scsi_handle_queue_ramp_up().

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Link: https://lore.kernel.org/r/20240305200503.57317-5-justintee8345@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>