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, 1 insertions, 175 deletions

diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index b492293d51f2..72918d227ead 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -112,7 +112,6 @@ static void sas_end_task(struct scsi_cmnd *sc, struct sas_task *task)
 
 	sc->result = (hs << 16) | stat;
 	ASSIGN_SAS_TASK(sc, NULL);
-	list_del_init(&task->list);
 	sas_free_task(task);
 }
 
@@ -138,7 +137,6 @@ static void sas_scsi_task_done(struct sas_task *task)
 
 	if (unlikely(!sc)) {
 		SAS_DPRINTK("task_done called with non existing SCSI cmnd!\n");
-		list_del_init(&task->list);
 		sas_free_task(task);
 		return;
 	}
@@ -179,31 +177,10 @@ static struct sas_task *sas_create_task(struct scsi_cmnd *cmd,
 	return task;
 }
 
-int sas_queue_up(struct sas_task *task)
-{
-	struct sas_ha_struct *sas_ha = task->dev->port->ha;
-	struct scsi_core *core = &sas_ha->core;
-	unsigned long flags;
-	LIST_HEAD(list);
-
-	spin_lock_irqsave(&core->task_queue_lock, flags);
-	if (sas_ha->lldd_queue_size < core->task_queue_size + 1) {
-		spin_unlock_irqrestore(&core->task_queue_lock, flags);
-		return -SAS_QUEUE_FULL;
-	}
-	list_add_tail(&task->list, &core->task_queue);
-	core->task_queue_size += 1;
-	spin_unlock_irqrestore(&core->task_queue_lock, flags);
-	wake_up_process(core->queue_thread);
-
-	return 0;
-}
-
 int sas_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 {
 	struct sas_internal *i = to_sas_internal(host->transportt);
 	struct domain_device *dev = cmd_to_domain_dev(cmd);
-	struct sas_ha_struct *sas_ha = dev->port->ha;
 	struct sas_task *task;
 	int res = 0;
 
@@ -224,12 +201,7 @@ int sas_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 	if (!task)
 		return SCSI_MLQUEUE_HOST_BUSY;
 
-	/* Queue up, Direct Mode or Task Collector Mode. */
-	if (sas_ha->lldd_max_execute_num < 2)
-		res = i->dft->lldd_execute_task(task, 1, GFP_ATOMIC);
-	else
-		res = sas_queue_up(task);
-
+	res = i->dft->lldd_execute_task(task, GFP_ATOMIC);
 	if (res)
 		goto out_free_task;
 	return 0;
@@ -323,37 +295,17 @@ enum task_disposition {
 	TASK_IS_DONE,
 	TASK_IS_ABORTED,
 	TASK_IS_AT_LU,
-	TASK_IS_NOT_AT_HA,
 	TASK_IS_NOT_AT_LU,
 	TASK_ABORT_FAILED,
 };
 
 static enum task_disposition sas_scsi_find_task(struct sas_task *task)
 {
-	struct sas_ha_struct *ha = task->dev->port->ha;
 	unsigned long flags;
 	int i, res;
 	struct sas_internal *si =
 		to_sas_internal(task->dev->port->ha->core.shost->transportt);
 
-	if (ha->lldd_max_execute_num > 1) {
-		struct scsi_core *core = &ha->core;
-		struct sas_task *t, *n;
-
-		mutex_lock(&core->task_queue_flush);
-		spin_lock_irqsave(&core->task_queue_lock, flags);
-		list_for_each_entry_safe(t, n, &core->task_queue, list)
-			if (task == t) {
-				list_del_init(&t->list);
-				break;
-			}
-		spin_unlock_irqrestore(&core->task_queue_lock, flags);
-		mutex_unlock(&core->task_queue_flush);
-
-		if (task == t)
-			return TASK_IS_NOT_AT_HA;
-	}
-
 	for (i = 0; i < 5; i++) {
 		SAS_DPRINTK("%s: aborting task 0x%p\n", __func__, task);
 		res = si->dft->lldd_abort_task(task);
@@ -667,14 +619,6 @@ static void sas_eh_handle_sas_errors(struct Scsi_Host *shost, struct list_head *
 		cmd->eh_eflags = 0;
 
 		switch (res) {
-		case TASK_IS_NOT_AT_HA:
-			SAS_DPRINTK("%s: task 0x%p is not at ha: %s\n",
-				    __func__, task,
-				    cmd->retries ? "retry" : "aborted");
-			if (cmd->retries)
-				cmd->retries--;
-			sas_eh_finish_cmd(cmd);
-			continue;
 		case TASK_IS_DONE:
 			SAS_DPRINTK("%s: task 0x%p is done\n", __func__,
 				    task);
@@ -836,9 +780,6 @@ retry:
 		scsi_eh_ready_devs(shost, &eh_work_q, &ha->eh_done_q);
 
 out:
-	if (ha->lldd_max_execute_num > 1)
-		wake_up_process(ha->core.queue_thread);
-
 	sas_eh_handle_resets(shost);
 
 	/* now link into libata eh --- if we have any ata devices */
@@ -984,121 +925,6 @@ int sas_bios_param(struct scsi_device *scsi_dev,
 	return 0;
 }
 
-/* ---------- Task Collector Thread implementation ---------- */
-
-static void sas_queue(struct sas_ha_struct *sas_ha)
-{
-	struct scsi_core *core = &sas_ha->core;
-	unsigned long flags;
-	LIST_HEAD(q);
-	int can_queue;
-	int res;
-	struct sas_internal *i = to_sas_internal(core->shost->transportt);
-
-	mutex_lock(&core->task_queue_flush);
-	spin_lock_irqsave(&core->task_queue_lock, flags);
-	while (!kthread_should_stop() &&
-	       !list_empty(&core->task_queue) &&
-	       !test_bit(SAS_HA_FROZEN, &sas_ha->state)) {
-
-		can_queue = sas_ha->lldd_queue_size - core->task_queue_size;
-		if (can_queue >= 0) {
-			can_queue = core->task_queue_size;
-			list_splice_init(&core->task_queue, &q);
-		} else {
-			struct list_head *a, *n;
-
-			can_queue = sas_ha->lldd_queue_size;
-			list_for_each_safe(a, n, &core->task_queue) {
-				list_move_tail(a, &q);
-				if (--can_queue == 0)
-					break;
-			}
-			can_queue = sas_ha->lldd_queue_size;
-		}
-		core->task_queue_size -= can_queue;
-		spin_unlock_irqrestore(&core->task_queue_lock, flags);
-		{
-			struct sas_task *task = list_entry(q.next,
-							   struct sas_task,
-							   list);
-			list_del_init(&q);
-			res = i->dft->lldd_execute_task(task, can_queue,
-							GFP_KERNEL);
-			if (unlikely(res))
-				__list_add(&q, task->list.prev, &task->list);
-		}
-		spin_lock_irqsave(&core->task_queue_lock, flags);
-		if (res) {
-			list_splice_init(&q, &core->task_queue); /*at head*/
-			core->task_queue_size += can_queue;
-		}
-	}
-	spin_unlock_irqrestore(&core->task_queue_lock, flags);
-	mutex_unlock(&core->task_queue_flush);
-}
-
-/**
- * sas_queue_thread -- The Task Collector thread
- * @_sas_ha: pointer to struct sas_ha
- */
-static int sas_queue_thread(void *_sas_ha)
-{
-	struct sas_ha_struct *sas_ha = _sas_ha;
-
-	while (1) {
-		set_current_state(TASK_INTERRUPTIBLE);
-		schedule();
-		sas_queue(sas_ha);
-		if (kthread_should_stop())
-			break;
-	}
-
-	return 0;
-}
-
-int sas_init_queue(struct sas_ha_struct *sas_ha)
-{
-	struct scsi_core *core = &sas_ha->core;
-
-	spin_lock_init(&core->task_queue_lock);
-	mutex_init(&core->task_queue_flush);
-	core->task_queue_size = 0;
-	INIT_LIST_HEAD(&core->task_queue);
-
-	core->queue_thread = kthread_run(sas_queue_thread, sas_ha,
-					 "sas_queue_%d", core->shost->host_no);
-	if (IS_ERR(core->queue_thread))
-		return PTR_ERR(core->queue_thread);
-	return 0;
-}
-
-void sas_shutdown_queue(struct sas_ha_struct *sas_ha)
-{
-	unsigned long flags;
-	struct scsi_core *core = &sas_ha->core;
-	struct sas_task *task, *n;
-
-	kthread_stop(core->queue_thread);
-
-	if (!list_empty(&core->task_queue))
-		SAS_DPRINTK("HA: %llx: scsi core task queue is NOT empty!?\n",
-			    SAS_ADDR(sas_ha->sas_addr));
-
-	spin_lock_irqsave(&core->task_queue_lock, flags);
-	list_for_each_entry_safe(task, n, &core->task_queue, list) {
-		struct scsi_cmnd *cmd = task->uldd_task;
-
-		list_del_init(&task->list);
-
-		ASSIGN_SAS_TASK(cmd, NULL);
-		sas_free_task(task);
-		cmd->result = DID_ABORT << 16;
-		cmd->scsi_done(cmd);
-	}
-	spin_unlock_irqrestore(&core->task_queue_lock, flags);
-}
-
 /*
  * Tell an upper layer that it needs to initiate an abort for a given task.
  * This should only ever be called by an LLDD.