Merge tag 'ata-6.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata

Pull ata fix from Damien Le Moal:

 - Fix ata_find_dev() use of the device number to find a struct
   ata_device for a port. This addresses issues with some passthrough
   commands with libsas managed devices.

* tag 'ata-6.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata:
  ata: libata-scsi: Use correct device no in ata_find_dev()

Author: torvalds

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;
 }