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>

4 files changed, 8 insertions, 21 deletions

diff --git a/drivers/scsi/aic94xx/aic94xx.h b/drivers/scsi/aic94xx/aic94xx.h
index 66cda669b417..26d4ad9ede2e 100644
--- a/drivers/scsi/aic94xx/aic94xx.h
+++ b/drivers/scsi/aic94xx/aic94xx.h
@@ -78,7 +78,7 @@ void asd_dev_gone(struct domain_device *dev);
 
 void asd_invalidate_edb(struct asd_ascb *ascb, int edb_id);
 
-int  asd_execute_task(struct sas_task *, int num, gfp_t gfp_flags);
+int  asd_execute_task(struct sas_task *task, gfp_t gfp_flags);
 
 void asd_set_dmamode(struct domain_device *dev);
 
diff --git a/drivers/scsi/aic94xx/aic94xx_hwi.c b/drivers/scsi/aic94xx/aic94xx_hwi.c
index 4df867e07b20..9f636a34d595 100644
--- a/drivers/scsi/aic94xx/aic94xx_hwi.c
+++ b/drivers/scsi/aic94xx/aic94xx_hwi.c
@@ -1200,8 +1200,7 @@ static void asd_start_scb_timers(struct list_head *list)
  * Case A: we can send the whole batch at once.  Increment "pending"
  * in the beginning of this function, when it is checked, in order to
  * eliminate races when this function is called by multiple processes.
- * Case B: should never happen if the managing layer considers
- * lldd_queue_size.
+ * Case B: should never happen.
  */
 int asd_post_ascb_list(struct asd_ha_struct *asd_ha, struct asd_ascb *ascb,
 		       int num)
diff --git a/drivers/scsi/aic94xx/aic94xx_init.c b/drivers/scsi/aic94xx/aic94xx_init.c
index a64cf932d03d..14fc018436c2 100644
--- a/drivers/scsi/aic94xx/aic94xx_init.c
+++ b/drivers/scsi/aic94xx/aic94xx_init.c
@@ -49,14 +49,6 @@ MODULE_PARM_DESC(use_msi, "\n"
 	"\tEnable(1) or disable(0) using PCI MSI.\n"
 	"\tDefault: 0");
 
-static int lldd_max_execute_num = 0;
-module_param_named(collector, lldd_max_execute_num, int, S_IRUGO);
-MODULE_PARM_DESC(collector, "\n"
-	"\tIf greater than one, tells the SAS Layer to run in Task Collector\n"
-	"\tMode.  If 1 or 0, tells the SAS Layer to run in Direct Mode.\n"
-	"\tThe aic94xx SAS LLDD supports both modes.\n"
-	"\tDefault: 0 (Direct Mode).\n");
-
 static struct scsi_transport_template *aic94xx_transport_template;
 static int asd_scan_finished(struct Scsi_Host *, unsigned long);
 static void asd_scan_start(struct Scsi_Host *);
@@ -711,9 +703,6 @@ static int asd_register_sas_ha(struct asd_ha_struct *asd_ha)
 	asd_ha->sas_ha.sas_port= sas_ports;
 	asd_ha->sas_ha.num_phys= ASD_MAX_PHYS;
 
-	asd_ha->sas_ha.lldd_queue_size = asd_ha->seq.can_queue;
-	asd_ha->sas_ha.lldd_max_execute_num = lldd_max_execute_num;
-
 	return sas_register_ha(&asd_ha->sas_ha);
 }
 
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;
 }