libata-sff: port_task is SFF specific

port_task is tightly bound to the standard SFF PIO HSM implementation.
Using it for any other purpose would be error-prone and there's no
such user and if some drivers need such feature, it would be much
better off using its own.  Move it inside CONFIG_ATA_SFF and rename it
to sff_pio_task.

The only function which is exposed to the core layer is
ata_sff_flush_pio_task() which is renamed from ata_port_flush_task()
and now also takes care of resetting hsm_task_state to HSM_ST_IDLE,
which is possible as it's now specific to PIO HSM.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 54 insertions, 18 deletions

diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 8a1396f52a3..e78ad76861f 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -40,6 +40,8 @@
 
 #include "libata.h"
 
+static struct workqueue_struct *ata_sff_wq;
+
 const struct ata_port_operations ata_sff_port_ops = {
 	.inherits		= &ata_base_port_ops,
 
@@ -1293,7 +1295,7 @@ fsm_start:
 		if (in_wq)
 			spin_unlock_irqrestore(ap->lock, flags);
 
-		/* if polling, ata_pio_task() handles the rest.
+		/* if polling, ata_sff_pio_task() handles the rest.
 		 * otherwise, interrupt handler takes over from here.
 		 */
 		break;
@@ -1458,14 +1460,38 @@ fsm_start:
 }
 EXPORT_SYMBOL_GPL(ata_sff_hsm_move);
 
-void ata_pio_task(struct work_struct *work)
+void ata_sff_queue_pio_task(struct ata_port *ap, unsigned long delay)
+{
+	/* may fail if ata_sff_flush_pio_task() in progress */
+	queue_delayed_work(ata_sff_wq, &ap->sff_pio_task,
+			   msecs_to_jiffies(delay));
+}
+EXPORT_SYMBOL_GPL(ata_sff_queue_pio_task);
+
+void ata_sff_flush_pio_task(struct ata_port *ap)
+{
+	DPRINTK("ENTER\n");
+
+	cancel_rearming_delayed_work(&ap->sff_pio_task);
+	ap->hsm_task_state = HSM_ST_IDLE;
+
+	if (ata_msg_ctl(ap))
+		ata_port_printk(ap, KERN_DEBUG, "%s: EXIT\n", __func__);
+}
+
+static void ata_sff_pio_task(struct work_struct *work)
 {
 	struct ata_port *ap =
-		container_of(work, struct ata_port, port_task.work);
-	struct ata_queued_cmd *qc = ap->port_task_data;
+		container_of(work, struct ata_port, sff_pio_task.work);
+	struct ata_queued_cmd *qc;
 	u8 status;
 	int poll_next;
 
+	/* qc can be NULL if timeout occurred */
+	qc = ata_qc_from_tag(ap, ap->link.active_tag);
+	if (!qc)
+		return;
+
 fsm_start:
 	WARN_ON_ONCE(ap->hsm_task_state == HSM_ST_IDLE);
 
@@ -1481,7 +1507,7 @@ fsm_start:
 		msleep(2);
 		status = ata_sff_busy_wait(ap, ATA_BUSY, 10);
 		if (status & ATA_BUSY) {
-			ata_pio_queue_task(ap, qc, ATA_SHORT_PAUSE);
+			ata_sff_queue_pio_task(ap, ATA_SHORT_PAUSE);
 			return;
 		}
 	}
@@ -1551,7 +1577,7 @@ unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
 		ap->hsm_task_state = HSM_ST_LAST;
 
 		if (qc->tf.flags & ATA_TFLAG_POLLING)
-			ata_pio_queue_task(ap, qc, 0);
+			ata_sff_queue_pio_task(ap, 0);
 
 		break;
 
@@ -1573,20 +1599,21 @@ unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
 		if (qc->tf.flags & ATA_TFLAG_WRITE) {
 			/* PIO data out protocol */
 			ap->hsm_task_state = HSM_ST_FIRST;
-			ata_pio_queue_task(ap, qc, 0);
+			ata_sff_queue_pio_task(ap, 0);
 
-			/* always send first data block using
-			 * the ata_pio_task() codepath.
+			/* always send first data block using the
+			 * ata_sff_pio_task() codepath.
 			 */
 		} else {
 			/* PIO data in protocol */
 			ap->hsm_task_state = HSM_ST;
 
 			if (qc->tf.flags & ATA_TFLAG_POLLING)
-				ata_pio_queue_task(ap, qc, 0);
+				ata_sff_queue_pio_task(ap, 0);
 
-			/* if polling, ata_pio_task() handles the rest.
-			 * otherwise, interrupt handler takes over from here.
+			/* if polling, ata_sff_pio_task() handles the
+			 * rest.  otherwise, interrupt handler takes
+			 * over from here.
 			 */
 		}
 
@@ -1604,7 +1631,7 @@ unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
 		/* send cdb by polling if no cdb interrupt */
 		if ((!(qc->dev->flags & ATA_DFLAG_CDB_INTR)) ||
 		    (qc->tf.flags & ATA_TFLAG_POLLING))
-			ata_pio_queue_task(ap, qc, 0);
+			ata_sff_queue_pio_task(ap, 0);
 		break;
 
 	case ATAPI_PROT_DMA:
@@ -1616,7 +1643,7 @@ unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
 
 		/* send cdb by polling if no cdb interrupt */
 		if (!(qc->dev->flags & ATA_DFLAG_CDB_INTR))
-			ata_pio_queue_task(ap, qc, 0);
+			ata_sff_queue_pio_task(ap, 0);
 		break;
 
 	default:
@@ -2360,8 +2387,6 @@ void ata_sff_error_handler(struct ata_port *ap)
 	/* reset PIO HSM and stop DMA engine */
 	spin_lock_irqsave(ap->lock, flags);
 
-	ap->hsm_task_state = HSM_ST_IDLE;
-
 	if (ap->ioaddr.bmdma_addr &&
 	    qc && (qc->tf.protocol == ATA_PROT_DMA ||
 		   qc->tf.protocol == ATAPI_PROT_DMA)) {
@@ -2432,8 +2457,6 @@ void ata_sff_post_internal_cmd(struct ata_queued_cmd *qc)
 
 	spin_lock_irqsave(ap->lock, flags);
 
-	ap->hsm_task_state = HSM_ST_IDLE;
-
 	if (ap->ioaddr.bmdma_addr)
 		ap->ops->bmdma_stop(qc);
 
@@ -3074,15 +3097,28 @@ EXPORT_SYMBOL_GPL(ata_pci_bmdma_init);
  */
 void ata_sff_port_init(struct ata_port *ap)
 {
+	INIT_DELAYED_WORK(&ap->sff_pio_task, ata_sff_pio_task);
 	ap->ctl = ATA_DEVCTL_OBS;
 	ap->last_ctl = 0xFF;
 }
 
 int __init ata_sff_init(void)
 {
+	/*
+	 * FIXME: In UP case, there is only one workqueue thread and if you
+	 * have more than one PIO device, latency is bloody awful, with
+	 * occasional multi-second "hiccups" as one PIO device waits for
+	 * another.  It's an ugly wart that users DO occasionally complain
+	 * about; luckily most users have at most one PIO polled device.
+	 */
+	ata_sff_wq = create_workqueue("ata_sff");
+	if (!ata_sff_wq)
+		return -ENOMEM;
+
 	return 0;
 }
 
 void __exit ata_sff_exit(void)
 {
+	destroy_workqueue(ata_sff_wq);
 }