[PATCH] libata-hp-prep: add ata_aux_wq

It's best to run ATA hotplug from EH but attaching SCSI devices needs
working EH.  ata_aux_wq is used to give SCSI hotplug operations a
separate context.
Signed-off-by: Tejun Heo <htejun@gmail.com>

drivers/scsi/libata-core.c

@@ -69,6 +69,8 @@ static void ata_dev_xfermask(struct ata_device *dev);
 static unsigned int ata_unique_id = 1;
 static struct workqueue_struct *ata_wq;
 
+struct workqueue_struct *ata_aux_wq;
+
 int atapi_enabled = 1;
 module_param(atapi_enabled, int, 0444);
 MODULE_PARM_DESC(atapi_enabled, "Enable discovery of ATAPI devices (0=off, 1=on)");
@@ -5623,6 +5625,12 @@ static int __init ata_init(void)
 	if (!ata_wq)
 		return -ENOMEM;
 
+	ata_aux_wq = create_singlethread_workqueue("ata_aux");
+	if (!ata_aux_wq) {
+		destroy_workqueue(ata_wq);
+		return -ENOMEM;
+	}
+
 	printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
 	return 0;
 }
@@ -5630,6 +5638,7 @@ static int __init ata_init(void)
 static void __exit ata_exit(void)
 {
 	destroy_workqueue(ata_wq);
+	destroy_workqueue(ata_aux_wq);
 }
 
 module_init(ata_init);

drivers/scsi/libata.h

@@ -39,6 +39,7 @@ struct ata_scsi_args {
 };
 
 /* libata-core.c */
+extern struct workqueue_struct *ata_aux_wq;
 extern int atapi_enabled;
 extern int atapi_dmadir;
 extern int libata_fua;