1 files changed, 38 insertions, 8 deletions

diff --git a/drivers/usb/storage/transport.c b/drivers/usb/storage/transport.c
index e20dc525d17..589f6b4404f 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;
+                        }
                 }
         }