6 files changed, 15 insertions, 30 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index ddf8e4862787..4f78741692dc 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -98,8 +98,6 @@ static unsigned long ata_dev_blacklisted(const struct ata_device *dev);
 
 unsigned int ata_print_id = 1;
 
-struct workqueue_struct *ata_aux_wq;
-
 struct ata_force_param {
         const char      *name;
         unsigned int    cbl;
@@ -5611,6 +5609,7 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
         ap->msg_enable = ATA_MSG_DRV | ATA_MSG_ERR | ATA_MSG_WARN;
 #endif
 
+        mutex_init(&ap->scsi_scan_mutex);
         INIT_DELAYED_WORK(&ap->hotplug_task, ata_scsi_hotplug);
         INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan);
         INIT_LIST_HEAD(&ap->eh_done_q);
@@ -6549,29 +6548,20 @@ static int __init ata_init(void)
 
         ata_parse_force_param();
 
-        ata_aux_wq = create_singlethread_workqueue("ata_aux");
-        if (!ata_aux_wq)
-                goto fail;
-
         rc = ata_sff_init();
-        if (rc)
-                goto fail;
+        if (rc) {
+                kfree(ata_force_tbl);
+                return rc;
+        }
 
         printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
         return 0;
-
-fail:
-        kfree(ata_force_tbl);
-        if (ata_aux_wq)
-                destroy_workqueue(ata_aux_wq);
-        return rc;
 }
 
 static void __exit ata_exit(void)
 {
         ata_sff_exit();
         kfree(ata_force_tbl);
-        destroy_workqueue(ata_aux_wq);
 }
 
 subsys_initcall(ata_init);
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index f77a67303f8b..4d2af824dd23 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -727,7 +727,7 @@ void ata_scsi_error(struct Scsi_Host *host)
         if (ap->pflags & ATA_PFLAG_LOADING)
                 ap->pflags &= ~ATA_PFLAG_LOADING;
         else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG)
-                queue_delayed_work(ata_aux_wq, &ap->hotplug_task, 0);
+                schedule_delayed_work(&ap->hotplug_task, 0);
 
         if (ap->pflags & ATA_PFLAG_RECOVERED)
                 ata_port_printk(ap, KERN_INFO, "EH complete\n");
@@ -2944,7 +2944,7 @@ static int ata_eh_revalidate_and_attach(struct ata_link *link,
                         ehc->i.flags |= ATA_EHI_SETMODE;
 
                         /* schedule the scsi_rescan_device() here */
-                        queue_work(ata_aux_wq, &(ap->scsi_rescan_task));
+                        schedule_work(&(ap->scsi_rescan_task));
                 } else if (dev->class == ATA_DEV_UNKNOWN &&
                            ehc->tries[dev->devno] &&
                            ata_class_enabled(ehc->classes[dev->devno])) {
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index a54273d2c3c6..d75c9c479d1a 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3435,7 +3435,7 @@ void ata_scsi_scan_host(struct ata_port *ap, int sync)
                                 "                  switching to async\n");
         }
 
-        queue_delayed_work(ata_aux_wq, &ap->hotplug_task,
+        queue_delayed_work(system_long_wq, &ap->hotplug_task,
                            round_jiffies_relative(HZ));
 }
 
@@ -3582,6 +3582,7 @@ void ata_scsi_hotplug(struct work_struct *work)
         }
 
         DPRINTK("ENTER\n");
+        mutex_lock(&ap->scsi_scan_mutex);
 
         /* Unplug detached devices.  We cannot use link iterator here
          * because PMP links have to be scanned even if PMP is
@@ -3595,6 +3596,7 @@ void ata_scsi_hotplug(struct work_struct *work)
         /* scan for new ones */
         ata_scsi_scan_host(ap, 0);
 
+        mutex_unlock(&ap->scsi_scan_mutex);
         DPRINTK("EXIT\n");
 }
 
@@ -3673,9 +3675,7 @@ static int ata_scsi_user_scan(struct Scsi_Host *shost, unsigned int channel,
  *      @work: Pointer to ATA port to perform scsi_rescan_device()
  *
  *      After ATA pass thru (SAT) commands are executed successfully,
- *      libata need to propagate the changes to SCSI layer.  This
- *      function must be executed from ata_aux_wq such that sdev
- *      attach/detach don't race with rescan.
+ *      libata need to propagate the changes to SCSI layer.
  *
  *      LOCKING:
  *      Kernel thread context (may sleep).
@@ -3688,6 +3688,7 @@ void ata_scsi_dev_rescan(struct work_struct *work)
         struct ata_device *dev;
         unsigned long flags;
 
+        mutex_lock(&ap->scsi_scan_mutex);
         spin_lock_irqsave(ap->lock, flags);
 
         ata_for_each_link(link, ap, EDGE) {
@@ -3707,6 +3708,7 @@ void ata_scsi_dev_rescan(struct work_struct *work)
         }
 
         spin_unlock_irqrestore(ap->lock, flags);
+        mutex_unlock(&ap->scsi_scan_mutex);
 }
 
 /**
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index efa4a18cfb9d..674c1436491f 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -3318,14 +3318,7 @@ void ata_sff_port_init(struct ata_port *ap)
 
 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");
+        ata_sff_wq = alloc_workqueue("ata_sff", WQ_RESCUER, WQ_MAX_ACTIVE);
         if (!ata_sff_wq)
                 return -ENOMEM;
 
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 4b84ed60324a..9ce1ecc63e39 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -54,7 +54,6 @@ enum {
 };
 
 extern unsigned int ata_print_id;
-extern struct workqueue_struct *ata_aux_wq;
 extern int atapi_passthru16;
 extern int libata_fua;
 extern int libata_noacpi;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index b85f3ff34d7d..f010f18a0f86 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -751,6 +751,7 @@ struct ata_port {
         struct ata_host         *host;
         struct device           *dev;
 
+        struct mutex            scsi_scan_mutex;
         struct delayed_work     hotplug_task;
         struct work_struct      scsi_rescan_task;