Merge tag 'ata-6.4-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata

Pull ata fix from Damien Le Moal:

 - Avoid deadlocks on resume from sleep by delaying scsi rescan until
   the scsi device is also fully resumed.

* tag 'ata-6.4-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata:
  ata: libata-scsi: Avoid deadlock on rescan after device resume

4 files changed, 25 insertions, 4 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 8bf612bdd61a5a..b4f246f0cac7f0 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5348,7 +5348,7 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
 
 	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_DELAYED_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan);
 	INIT_LIST_HEAD(&ap->eh_done_q);
 	init_waitqueue_head(&ap->eh_wait_q);
 	init_completion(&ap->park_req_pending);
@@ -5954,6 +5954,7 @@ static void ata_port_detach(struct ata_port *ap)
 	WARN_ON(!(ap->pflags & ATA_PFLAG_UNLOADED));
 
 	cancel_delayed_work_sync(&ap->hotplug_task);
+	cancel_delayed_work_sync(&ap->scsi_rescan_task);
 
  skip_eh:
 	/* clean up zpodd on port removal */
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index a6c90181180271..6f8d1419159394 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2984,7 +2984,7 @@ static int ata_eh_revalidate_and_attach(struct ata_link *link,
 			ehc->i.flags |= ATA_EHI_SETMODE;
 
 			/* schedule the scsi_rescan_device() here */
-			schedule_work(&(ap->scsi_rescan_task));
+			schedule_delayed_work(&ap->scsi_rescan_task, 0);
 		} 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 8ce90284eb344b..551077cea4e4e0 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -4597,10 +4597,11 @@ int ata_scsi_user_scan(struct Scsi_Host *shost, unsigned int channel,
 void ata_scsi_dev_rescan(struct work_struct *work)
 {
 	struct ata_port *ap =
-		container_of(work, struct ata_port, scsi_rescan_task);
+		container_of(work, struct ata_port, scsi_rescan_task.work);
 	struct ata_link *link;
 	struct ata_device *dev;
 	unsigned long flags;
+	bool delay_rescan = false;
 
 	mutex_lock(&ap->scsi_scan_mutex);
 	spin_lock_irqsave(ap->lock, flags);
@@ -4614,6 +4615,21 @@ void ata_scsi_dev_rescan(struct work_struct *work)
 			if (scsi_device_get(sdev))
 				continue;
 
+			/*
+			 * If the rescan work was scheduled because of a resume
+			 * event, the port is already fully resumed, but the
+			 * SCSI device may not yet be fully resumed. In such
+			 * case, executing scsi_rescan_device() may cause a
+			 * deadlock with the PM code on device_lock(). Prevent
+			 * this by giving up and retrying rescan after a short
+			 * delay.
+			 */
+			delay_rescan = sdev->sdev_gendev.power.is_suspended;
+			if (delay_rescan) {
+				scsi_device_put(sdev);
+				break;
+			}
+
 			spin_unlock_irqrestore(ap->lock, flags);
 			scsi_rescan_device(&(sdev->sdev_gendev));
 			scsi_device_put(sdev);
@@ -4623,4 +4639,8 @@ void ata_scsi_dev_rescan(struct work_struct *work)
 
 	spin_unlock_irqrestore(ap->lock, flags);
 	mutex_unlock(&ap->scsi_scan_mutex);
+
+	if (delay_rescan)
+		schedule_delayed_work(&ap->scsi_rescan_task,
+				      msecs_to_jiffies(5));
 }
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 311cd93377c75e..dd5797fb6305cb 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -836,7 +836,7 @@ struct ata_port {
 
 	struct mutex		scsi_scan_mutex;
 	struct delayed_work	hotplug_task;
-	struct work_struct	scsi_rescan_task;
+	struct delayed_work	scsi_rescan_task;
 
 	unsigned int		hsm_task_state;