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, 6 insertions, 7 deletions

diff --git a/drivers/scsi/aic94xx/aic94xx_task.c b/drivers/scsi/aic94xx/aic94xx_task.c
index 59b86e260ce9..5ff1ce7ba1f4 100644
--- a/drivers/scsi/aic94xx/aic94xx_task.c
+++ b/drivers/scsi/aic94xx/aic94xx_task.c
@@ -543,8 +543,7 @@ static int asd_can_queue(struct asd_ha_struct *asd_ha, int num)
 	return res;
 }
 
-int asd_execute_task(struct sas_task *task, const int num,
-		     gfp_t gfp_flags)
+int asd_execute_task(struct sas_task *task, gfp_t gfp_flags)
 {
 	int res = 0;
 	LIST_HEAD(alist);
@@ -553,11 +552,11 @@ int asd_execute_task(struct sas_task *task, const int num,
 	struct asd_ha_struct *asd_ha = task->dev->port->ha->lldd_ha;
 	unsigned long flags;
 
-	res = asd_can_queue(asd_ha, num);
+	res = asd_can_queue(asd_ha, 1);
 	if (res)
 		return res;
 
-	res = num;
+	res = 1;
 	ascb = asd_ascb_alloc_list(asd_ha, &res, gfp_flags);
 	if (res) {
 		res = -ENOMEM;
@@ -568,7 +567,7 @@ int asd_execute_task(struct sas_task *task, const int num,
 	list_for_each_entry(a, &alist, list) {
 		a->uldd_task = t;
 		t->lldd_task = a;
-		t = list_entry(t->list.next, struct sas_task, list);
+		break;
 	}
 	list_for_each_entry(a, &alist, list) {
 		t = a->uldd_task;
@@ -601,7 +600,7 @@ int asd_execute_task(struct sas_task *task, const int num,
 	}
 	list_del_init(&alist);
 
-	res = asd_post_ascb_list(asd_ha, ascb, num);
+	res = asd_post_ascb_list(asd_ha, ascb, 1);
 	if (unlikely(res)) {
 		a = NULL;
 		__list_add(&alist, ascb->list.prev, &ascb->list);
@@ -639,6 +638,6 @@ out_err_unmap:
 out_err:
 	if (ascb)
 		asd_ascb_free_list(ascb);
-	asd_can_dequeue(asd_ha, num);
+	asd_can_dequeue(asd_ha, 1);
 	return res;
 }