libsas: remove task_collector mode

The task_collector mode (or "latency_injector", (C) Dan Willians) is an
optional I/O path in libsas that queues up scsi commands instead of
directly sending it to the hardware.  It generall increases latencies
to in the optiomal case slightly reduce mmio traffic to the hardware.

Only the obsolete aic94xx driver and the mvsas driver allowed to use
it without recompiling the kernel, and most drivers didn't support it
at all.

Remove the giant blob of code to allow better optimizations for scsi-mq
in the future.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 5 insertions, 17 deletions

diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c
index 76570e6..b93f289 100644
--- a/drivers/scsi/pm8001/pm8001_sas.c
+++ b/drivers/scsi/pm8001/pm8001_sas.c
@@ -350,7 +350,7 @@ static int sas_find_local_port_id(struct domain_device *dev)
   */
 #define DEV_IS_GONE(pm8001_dev)	\
 	((!pm8001_dev || (pm8001_dev->dev_type == SAS_PHY_UNUSED)))
-static int pm8001_task_exec(struct sas_task *task, const int num,
+static int pm8001_task_exec(struct sas_task *task,
 	gfp_t gfp_flags, int is_tmf, struct pm8001_tmf_task *tmf)
 {
 	struct domain_device *dev = task->dev;
@@ -360,7 +360,6 @@ static int pm8001_task_exec(struct sas_task *task, const int num,
 	struct sas_task *t = task;
 	struct pm8001_ccb_info *ccb;
 	u32 tag = 0xdeadbeef, rc, n_elem = 0;
-	u32 n = num;
 	unsigned long flags = 0;
 
 	if (!dev->port) {
@@ -387,18 +386,12 @@ static int pm8001_task_exec(struct sas_task *task, const int num,
 				spin_unlock_irqrestore(&pm8001_ha->lock, flags);
 				t->task_done(t);
 				spin_lock_irqsave(&pm8001_ha->lock, flags);
-				if (n > 1)
-					t = list_entry(t->list.next,
-							struct sas_task, list);
 				continue;
 			} else {
 				struct task_status_struct *ts = &t->task_status;
 				ts->resp = SAS_TASK_UNDELIVERED;
 				ts->stat = SAS_PHY_DOWN;
 				t->task_done(t);
-				if (n > 1)
-					t = list_entry(t->list.next,
-							struct sas_task, list);
 				continue;
 			}
 		}
@@ -460,9 +453,7 @@ static int pm8001_task_exec(struct sas_task *task, const int num,
 		t->task_state_flags |= SAS_TASK_AT_INITIATOR;
 		spin_unlock(&t->task_state_lock);
 		pm8001_dev->running_req++;
-		if (n > 1)
-			t = list_entry(t->list.next, struct sas_task, list);
-	} while (--n);
+	} while (0);
 	rc = 0;
 	goto out_done;
 
@@ -483,14 +474,11 @@ out_done:
   * pm8001_queue_command - register for upper layer used, all IO commands sent
   * to HBA are from this interface.
   * @task: the task to be execute.
-  * @num: if can_queue great than 1, the task can be queued up. for SMP task,
-  * we always execute one one time
   * @gfp_flags: gfp_flags
   */
-int pm8001_queue_command(struct sas_task *task, const int num,
-		gfp_t gfp_flags)
+int pm8001_queue_command(struct sas_task *task, gfp_t gfp_flags)
 {
-	return pm8001_task_exec(task, num, gfp_flags, 0, NULL);
+	return pm8001_task_exec(task, gfp_flags, 0, NULL);
 }
 
 /**
@@ -708,7 +696,7 @@ static int pm8001_exec_internal_tmf_task(struct domain_device *dev,
 		task->slow_task->timer.expires = jiffies + PM8001_TASK_TIMEOUT*HZ;
 		add_timer(&task->slow_task->timer);
 
-		res = pm8001_task_exec(task, 1, GFP_KERNEL, 1, tmf);
+		res = pm8001_task_exec(task, GFP_KERNEL, 1, tmf);
 
 		if (res) {
 			del_timer(&task->slow_task->timer);