[PATCH] USB Storage: port reset on transport error

This patch causes a port reset whenever there's a transport error or abort.
If that fails it reverts back to doing a mass-storage device reset.  It
started life as as497 and was rediffed by me.

This makes error recovery a lot quicker and more reliable.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/storage/scsiglue.c

@@ -255,50 +255,23 @@ static int device_reset(struct scsi_cmnd *srb)
 
 	/* lock the device pointers and do the reset */
 	down(&(us->dev_semaphore));
-	if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
-		result = FAILED;
-		US_DEBUGP("No reset during disconnect\n");
-	} else
 	result = us->transport_reset(us);
 	up(&(us->dev_semaphore));
 
-	return result;
+	return result < 0 ? FAILED : SUCCESS;
 }
 
-/* This resets the device's USB port. */
-/* It refuses to work if there's more than one interface in
- * the device, so that other users are not affected. */
+/* Simulate a SCSI bus reset by resetting the device's USB port. */
 /* This is always called with scsi_lock(host) held */
 static int bus_reset(struct scsi_cmnd *srb)
 {
 	struct us_data *us = host_to_us(srb->device->host);
-	int result, rc;
+	int result;
 
 	US_DEBUGP("%s called\n", __FUNCTION__);
 
-	/* The USB subsystem doesn't handle synchronisation between
-	 * a device's several drivers. Therefore we reset only devices
-	 * with just one interface, which we of course own. */
-
 	down(&(us->dev_semaphore));
-	if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
-		result = -EIO;
-		US_DEBUGP("No reset during disconnect\n");
-	} else if (us->pusb_dev->actconfig->desc.bNumInterfaces != 1) {
-		result = -EBUSY;
-		US_DEBUGP("Refusing to reset a multi-interface device\n");
-	} else {
-		rc = usb_lock_device_for_reset(us->pusb_dev, us->pusb_intf);
-		if (rc < 0) {
-			US_DEBUGP("unable to lock device for reset: %d\n", rc);
-			result = rc;
-		} else {
-			result = usb_reset_device(us->pusb_dev);
-			if (rc)
-				usb_unlock_device(us->pusb_dev);
-			US_DEBUGP("usb_reset_device returns %d\n", result);
-		}
-	}
+	result = usb_stor_port_reset(us);
 	up(&(us->dev_semaphore));
 
 	/* lock the host for the return */
@@ -320,6 +293,14 @@ void usb_stor_report_device_reset(struct us_data *us)
 	}
 }
 
+/* Report a driver-initiated bus reset to the SCSI layer.
+ * Calling this for a SCSI-initiated reset is unnecessary but harmless.
+ * The caller must own the SCSI host lock. */
+void usb_stor_report_bus_reset(struct us_data *us)
+{
+	scsi_report_bus_reset(us_to_host(us), 0);
+}
+
 /***********************************************************************
  * /proc/scsi/ functions
  ***********************************************************************/

drivers/usb/storage/scsiglue.h

@@ -42,6 +42,7 @@
 #define _SCSIGLUE_H_
 
 extern void usb_stor_report_device_reset(struct us_data *us);
+extern void usb_stor_report_bus_reset(struct us_data *us);
 
 extern unsigned char usb_stor_sense_invalidCDB[18];
 extern struct scsi_host_template usb_stor_host_template;

drivers/usb/storage/transport.c

@@ -541,15 +541,15 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 	 */
 	if (test_bit(US_FLIDX_TIMED_OUT, &us->flags)) {
 		US_DEBUGP("-- command was aborted\n");
-		goto Handle_Abort;
+		srb->result = DID_ABORT << 16;
+		goto Handle_Errors;
 	}
 
 	/* if there is a transport error, reset and don't auto-sense */
 	if (result == USB_STOR_TRANSPORT_ERROR) {
 		US_DEBUGP("-- transport indicates error, resetting\n");
-		us->transport_reset(us);
 		srb->result = DID_ERROR << 16;
-		return;
+		goto Handle_Errors;
 	}
 
 	/* if the transport provided its own sense data, don't auto-sense */
@@ -669,7 +669,8 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 
 		if (test_bit(US_FLIDX_TIMED_OUT, &us->flags)) {
 			US_DEBUGP("-- auto-sense aborted\n");
-			goto Handle_Abort;
+			srb->result = DID_ABORT << 16;
+			goto Handle_Errors;
 		}
 		if (temp_result != USB_STOR_TRANSPORT_GOOD) {
 			US_DEBUGP("-- auto-sense failure\n");
@@ -678,9 +679,9 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 			 * multi-target device, since failure of an
 			 * auto-sense is perfectly valid
 			 */
-			if (!(us->flags & US_FL_SCM_MULT_TARG))
-				us->transport_reset(us);
 			srb->result = DID_ERROR << 16;
+			if (!(us->flags & US_FL_SCM_MULT_TARG))
+				goto Handle_Errors;
 			return;
 		}
 
@@ -721,12 +722,28 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 
 	return;
 
-	/* abort processing: the bulk-only transport requires a reset
-	 * following an abort */
-  Handle_Abort:
-	srb->result = DID_ABORT << 16;
-	if (us->protocol == US_PR_BULK)
+	/* Error and abort processing: try to resynchronize with the device
+	 * by issuing a port reset.  If that fails, try a class-specific
+	 * device reset. */
+  Handle_Errors:
+
+	/* Let the SCSI layer know we are doing a reset, set the
+	 * RESETTING bit, and clear the ABORTING bit so that the reset
+	 * may proceed. */
+	scsi_lock(us_to_host(us));
+	usb_stor_report_bus_reset(us);
+	set_bit(US_FLIDX_RESETTING, &us->flags);
+	clear_bit(US_FLIDX_ABORTING, &us->flags);
+	scsi_unlock(us_to_host(us));
+
+	result = usb_stor_port_reset(us);
+	if (result < 0) {
+		scsi_lock(us_to_host(us));
+		usb_stor_report_device_reset(us);
+		scsi_unlock(us_to_host(us));
 		us->transport_reset(us);
+	}
+	clear_bit(US_FLIDX_RESETTING, &us->flags);
 }
 
 /* Stop the current URB transfer */
@@ -1134,24 +1151,18 @@ static int usb_stor_reset_common(struct us_data *us,
 {
 	int result;
 	int result2;
-	int rc = FAILED;
 
-	/* Let the SCSI layer know we are doing a reset, set the
-	 * RESETTING bit, and clear the ABORTING bit so that the reset
-	 * may proceed.
-	 */
-	scsi_lock(us_to_host(us));
-	usb_stor_report_device_reset(us);
-	set_bit(US_FLIDX_RESETTING, &us->flags);
-	clear_bit(US_FLIDX_ABORTING, &us->flags);
-	scsi_unlock(us_to_host(us));
+	if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
+		US_DEBUGP("No reset during disconnect\n");
+		return -EIO;
+	}
 
 	result = usb_stor_control_msg(us, us->send_ctrl_pipe,
 			request, requesttype, value, index, data, size,
 			5*HZ);
 	if (result < 0) {
 		US_DEBUGP("Soft reset failed: %d\n", result);
-		goto Done;
+		return result;
 	}
 
  	/* Give the device some time to recover from the reset,
@@ -1161,7 +1172,7 @@ static int usb_stor_reset_common(struct us_data *us,
  			HZ*6);
 	if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
 		US_DEBUGP("Reset interrupted by disconnect\n");
-		goto Done;
+		return -EIO;
 	}
 
 	US_DEBUGP("Soft reset: clearing bulk-in endpoint halt\n");
@@ -1173,16 +1184,11 @@ static int usb_stor_reset_common(struct us_data *us,
 	/* return a result code based on the result of the clear-halts */
 	if (result >= 0)
 		result = result2;
-	if (result < 0) {
+	if (result < 0)
 		US_DEBUGP("Soft reset failed\n");
-		goto Done;
-	}
+	else
 		US_DEBUGP("Soft reset done\n");
-	rc = SUCCESS;
-
-  Done:
-	clear_bit(US_FLIDX_RESETTING, &us->flags);
-	return rc;
+	return result;
 }
 
 /* This issues a CB[I] Reset to the device in question
@@ -1212,3 +1218,32 @@ int usb_stor_Bulk_reset(struct us_data *us)
 				 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 				 0, us->ifnum, NULL, 0);
 }
+
+/* Issue a USB port reset to the device.  But don't do anything if
+ * there's more than one interface in the device, so that other users
+ * are not affected. */
+int usb_stor_port_reset(struct us_data *us)
+{
+	int result, rc;
+
+	if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
+		result = -EIO;
+		US_DEBUGP("No reset during disconnect\n");
+	} else if (us->pusb_dev->actconfig->desc.bNumInterfaces != 1) {
+		result = -EBUSY;
+		US_DEBUGP("Refusing to reset a multi-interface device\n");
+	} else {
+		result = rc =
+			usb_lock_device_for_reset(us->pusb_dev, us->pusb_intf);
+		if (result < 0) {
+			US_DEBUGP("unable to lock device for reset: %d\n",
+					result);
+		} else {
+			result = usb_reset_device(us->pusb_dev);
+			if (rc)
+				usb_unlock_device(us->pusb_dev);
+			US_DEBUGP("usb_reset_device returns %d\n", result);
+		}
+	}
+	return result;
+}

drivers/usb/storage/transport.h

@@ -171,4 +171,5 @@ extern int usb_stor_bulk_transfer_buf(struct us_data *us, unsigned int pipe,
 extern int usb_stor_bulk_transfer_sg(struct us_data *us, unsigned int pipe,
 		void *buf, unsigned int length, int use_sg, int *residual);
 
+extern int usb_stor_port_reset(struct us_data *us);
 #endif