usb-storage: Workaround devices with bogus sense size

usb-storage: Workaround devices with bogus sense size

Some devices, such as Huawei E169, advertise more than the standard
amount of sense data, causing us to set US_FL_SANE_SENSE, assuming
they support it. However, they subsequently fail the request sense
with that size.

This works around it generically. When a sense request fails due to
a device returning an error, US_FL_SANE_SENSE was set, and that sense
request used a larger sense size, we retry with a smaller size before
giving up.

Based on an original patch by Ben Efros <ben@pc-doctor.com>

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/storage/transport.c b/drivers/usb/storage/transport.c
index 3a4fb02..589f6b4 100644 (file)
--- 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");