[libata] move ATAPI startup from katad thread to workqueue thread

libata creates one thread per ata_port structure.  This is inadequate
for our needs, and also cumbersome to maintain, now that workqueues
and Rusty's thread work is available.

This patch begins to move libata away from doing its own per-port
thread, by moving the ATAPI command initiation code to work under
the workqueue system.

This patch also creates a private workqueue, global to all of libata.

drivers/scsi/libata-core.c

@@ -35,6 +35,7 @@
 #include <linux/timer.h>
 #include <linux/interrupt.h>
 #include <linux/suspend.h>
+#include <linux/workqueue.h>
 #include <scsi/scsi.h>
 #include "scsi.h"
 #include "hosts.h"
@@ -44,7 +45,6 @@
 
 #include "libata.h"
 
-static void atapi_cdb_send(struct ata_port *ap);
 static unsigned int ata_busy_sleep (struct ata_port *ap,
 				    unsigned long tmout_pat,
 			    	    unsigned long tmout);
@@ -59,6 +59,7 @@ static void ata_set_mode(struct ata_port *ap);
 static int ata_qc_issue_prot(struct ata_queued_cmd *qc);
 
 static unsigned int ata_unique_id = 1;
+struct workqueue_struct *ata_wq = NULL;
 
 MODULE_AUTHOR("Jeff Garzik");
 MODULE_DESCRIPTION("Library module for ATA devices");
@@ -78,7 +79,6 @@ static const char * thr_state_name[] = {
 	"THR_PIO_LAST",
 	"THR_PIO_LAST_POLL",
 	"THR_PIO_ERR",
-	"THR_PACKET",
 };
 
 /**
@@ -2785,10 +2785,6 @@ static unsigned long ata_thread_iter(struct ata_port *ap)
 		timeout = 11 * HZ;
 		break;
 
-	case THR_PACKET:
-		atapi_cdb_send(ap);
-		break;
-
 	default:
 		printk(KERN_DEBUG "ata%u: unknown thr state %s\n",
 		       ap->id, ata_thr_state_name(ap->thr_state));
@@ -2825,10 +2821,10 @@ static int ata_thread (void *data)
 
                 if (signal_pending (current))
                         flush_signals(current);
-                        
+
                 if (current->flags & PF_FREEZE)
 			refrigerator(PF_FREEZE);
-                                                        
+
 
                 if ((timeout < 0) || (ap->time_to_die))
                         break;
@@ -2879,8 +2875,8 @@ static int ata_thread_kill(struct ata_port *ap)
 }
 
 /**
- *	atapi_cdb_send - Write CDB bytes to hardware
- *	@ap: Port to which ATAPI device is attached.
+ *	atapi_packet_task - Write CDB bytes to hardware
+ *	@_data: Port to which ATAPI device is attached.
  *
  *	When device has indicated its readiness to accept
  *	a CDB, this function is called.  Send the CDB.
@@ -2892,8 +2888,9 @@ static int ata_thread_kill(struct ata_port *ap)
  *	Kernel thread context (may sleep)
  */
 
-static void atapi_cdb_send(struct ata_port *ap)
+static void atapi_packet_task(void *_data)
 {
+	struct ata_port *ap = _data;
 	struct ata_queued_cmd *qc;
 	u8 status;
 
@@ -2917,6 +2914,8 @@ static void atapi_cdb_send(struct ata_port *ap)
 	outsl(ap->ioaddr.data_addr,
 	      qc->scsicmd->cmnd, ap->host->max_cmd_len / 4);
 
+	/* FIXME: start DMA here */
+
 	/* if we are DMA'ing, irq handler takes over from here */
 	if (qc->tf.feature == ATAPI_PKT_DMA)
 		goto out;
@@ -2951,7 +2950,7 @@ int ata_port_start (struct ata_port *ap)
 	ap->prd = pci_alloc_consistent(pdev, ATA_PRD_TBL_SZ, &ap->prd_dma);
 	if (!ap->prd)
 		return -ENOMEM;
-	
+
 	DPRINTK("prd alloc, virt %p, dma %llx\n", ap->prd, (unsigned long long) ap->prd_dma);
 
 	return 0;
@@ -3029,6 +3028,7 @@ static void ata_host_init(struct ata_port *ap, struct Scsi_Host *host,
 	/* ata_engine init */
 	ap->eng.flags = 0;
 	INIT_LIST_HEAD(&ap->eng.q);
+	INIT_WORK(&ap->packet_task, atapi_packet_task, ap);
 
 	for (i = 0; i < ATA_MAX_DEVICES; i++)
 		ap->device[i].devno = i;
@@ -3557,11 +3557,21 @@ int pci_test_config_bits(struct pci_dev *pdev, struct pci_bits *bits)
 
 static int __init ata_init(void)
 {
+	ata_wq = create_workqueue("ata");
+	if (!ata_wq)
+		return -ENOMEM;
+
 	printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
 	return 0;
 }
 
+static void __exit ata_exit(void)
+{
+	destroy_workqueue(ata_wq);
+}
+
 module_init(ata_init);
+module_exit(ata_exit);
 
 /*
  * libata is essentially a library of internal helper functions for

drivers/scsi/libata-scsi.c

@@ -29,6 +29,7 @@
 #include "scsi.h"
 #include "hosts.h"
 #include <linux/libata.h>
+#include <linux/workqueue.h>
 
 #include "libata.h"
 
@@ -950,7 +951,7 @@ static void atapi_scsi_queuecmd(struct ata_port *ap, struct ata_device *dev,
 
 	status = ata_busy_wait(ap, ATA_BUSY, 1000);
 	if (status & ATA_BUSY) {
-		ata_thread_wake(ap, THR_PACKET);
+		queue_work(ata_wq, &ap->packet_task);
 		return;
 	}
 	if ((status & ATA_DRQ) == 0)
@@ -961,7 +962,7 @@ static void atapi_scsi_queuecmd(struct ata_port *ap, struct ata_device *dev,
 	outsl(ap->ioaddr.data_addr, scsicmd, ap->host->max_cmd_len / 4);
 
 	if (!doing_dma)
-		ata_thread_wake(ap, THR_PACKET);
+		queue_work(ata_wq, &ap->packet_task);
 
 	VPRINTK("EXIT\n");
 	return;

drivers/scsi/libata.h

@@ -35,6 +35,7 @@ struct ata_scsi_args {
 	void			(*done)(struct scsi_cmnd *);
 };
 
+extern struct workqueue_struct *ata_wq;
 
 /* libata-core.c */
 extern void ata_dev_id_string(struct ata_device *dev, unsigned char *s,

include/linux/libata.h

@@ -27,6 +27,7 @@
 #include <linux/interrupt.h>
 #include <asm/io.h>
 #include <linux/ata.h>
+#include <linux/workqueue.h>
 
 /*
  * compile-time options
@@ -150,7 +151,6 @@ enum {
 	THR_PIO_LAST		= (THR_PIO + 1),
 	THR_PIO_LAST_POLL	= (THR_PIO_LAST + 1),
 	THR_PIO_ERR		= (THR_PIO_LAST_POLL + 1),
-	THR_PACKET		= (THR_PIO_ERR + 1),
 
 	/* SATA port states */
 	PORT_UNKNOWN		= 0,
@@ -317,6 +317,8 @@ struct ata_port {
 	struct timer_list	thr_timer;
 	unsigned long		thr_timeout;
 
+	struct work_struct	packet_task;
+
 	void			*private_data;
 };