1 files changed, 38 insertions, 8 deletions

diff --git a/drivers/usb/storage/transport.c b/drivers/usb/storage/transport.c
index e20dc525d177..589f6b4404f0 100644
--- a/drivers/usb/storage/transport.c
+++ b/drivers/usb/storage/transport.c
@@ -696,7 +696,7 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 		/* device supports and needs bigger sense buffer */
 		if (us->fflags & US_FL_SANE_SENSE)
 			sense_size = ~0;
-
+Retry_Sense:
 		US_DEBUGP("Issuing auto-REQUEST_SENSE\n");
 
 		scsi_eh_prep_cmnd(srb, &ses, NULL, 0, sense_size);
@@ -720,6 +720,21 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 			srb->result = DID_ABORT << 16;
 			goto Handle_Errors;
 		}
+
+		/* Some devices claim to support larger sense but fail when
+		 * trying to request it. When a transport failure happens
+		 * using US_FS_SANE_SENSE, we always retry with a standard
+		 * (small) sense request. This fixes some USB GSM modems
+		 */
+		if (temp_result == USB_STOR_TRANSPORT_FAILED &&
+		    (us->fflags & US_FL_SANE_SENSE) &&
+		    sense_size != US_SENSE_SIZE) {
+			US_DEBUGP("-- auto-sense failure, retry small sense\n");
+			sense_size = US_SENSE_SIZE;
+			goto Retry_Sense;
+		}
+
+		/* Other failures */
 		if (temp_result != USB_STOR_TRANSPORT_GOOD) {
 			US_DEBUGP("-- auto-sense failure\n");
 
@@ -768,17 +783,32 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 		/* set the result so the higher layers expect this data */
 		srb->result = SAM_STAT_CHECK_CONDITION;
 
-		/* If things are really okay, then let's show that.  Zero
-		 * out the sense buffer so the higher layers won't realize
-		 * we did an unsolicited auto-sense. */
-		if (result == USB_STOR_TRANSPORT_GOOD &&
-			/* Filemark 0, ignore EOM, ILI 0, no sense */
+		/* We often get empty sense data.  This could indicate that
+		 * everything worked or that there was an unspecified
+		 * problem.  We have to decide which.
+		 */
+		if (	/* Filemark 0, ignore EOM, ILI 0, no sense */
 				(srb->sense_buffer[2] & 0xaf) == 0 &&
 			/* No ASC or ASCQ */
 				srb->sense_buffer[12] == 0 &&
 				srb->sense_buffer[13] == 0) {
-			srb->result = SAM_STAT_GOOD;
-			srb->sense_buffer[0] = 0x0;
+
+			/* If things are really okay, then let's show that.
+			 * Zero out the sense buffer so the higher layers
+			 * won't realize we did an unsolicited auto-sense.
+			 */
+			if (result == USB_STOR_TRANSPORT_GOOD) {
+				srb->result = SAM_STAT_GOOD;
+				srb->sense_buffer[0] = 0x0;
+
+			/* If there was a problem, report an unspecified
+			 * hardware error to prevent the higher layers from
+			 * entering an infinite retry loop.
+			 */
+			} else {
+				srb->result = DID_ERROR << 16;
+				srb->sense_buffer[2] = HARDWARE_ERROR;
+			}
 		}
 	}