1 files changed, 47 insertions, 9 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 7bb12deab70c..551077cea4e4 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2694,18 +2694,36 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
 	return 0;
 }
 
-static struct ata_device *ata_find_dev(struct ata_port *ap, int devno)
+static struct ata_device *ata_find_dev(struct ata_port *ap, unsigned int devno)
 {
-	if (!sata_pmp_attached(ap)) {
-		if (likely(devno >= 0 &&
-			   devno < ata_link_max_devices(&ap->link)))
+	/*
+	 * For the non-PMP case, ata_link_max_devices() returns 1 (SATA case),
+	 * or 2 (IDE master + slave case). However, the former case includes
+	 * libsas hosted devices which are numbered per scsi host, leading
+	 * to devno potentially being larger than 0 but with each struct
+	 * ata_device having its own struct ata_port and struct ata_link.
+	 * To accommodate these, ignore devno and always use device number 0.
+	 */
+	if (likely(!sata_pmp_attached(ap))) {
+		int link_max_devices = ata_link_max_devices(&ap->link);
+
+		if (link_max_devices == 1)
+			return &ap->link.device[0];
+
+		if (devno < link_max_devices)
 			return &ap->link.device[devno];
-	} else {
-		if (likely(devno >= 0 &&
-			   devno < ap->nr_pmp_links))
-			return &ap->pmp_link[devno].device[0];
+
+		return NULL;
 	}
 
+	/*
+	 * For PMP-attached devices, the device number corresponds to C
+	 * (channel) of SCSI [H:C:I:L], indicating the port pmp link
+	 * for the device.
+	 */
+	if (devno < ap->nr_pmp_links)
+		return &ap->pmp_link[devno].device[0];
+
 	return NULL;
 }
 
@@ -4579,10 +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);
@@ -4596,6 +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);
@@ -4605,4 +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));
 }