[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>

4 files changed, 82 insertions, 64 deletions

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index e43eddc3d44b..da2bfa944b96 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/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);
+        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
  ***********************************************************************/
diff --git a/drivers/usb/storage/scsiglue.h b/drivers/usb/storage/scsiglue.h
index d0a49af026c4..737e4fa6045f 100644
--- a/drivers/usb/storage/scsiglue.h
+++ b/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;
diff --git a/drivers/usb/storage/transport.c b/drivers/usb/storage/transport.c
index 419afb2216b9..e6b1c6cf07f2 100644
--- a/drivers/usb/storage/transport.c
+++ b/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;
-        }
-        US_DEBUGP("Soft reset done\n");
-        rc = SUCCESS;
-
-  Done:
-        clear_bit(US_FLIDX_RESETTING, &us->flags);
-        return rc;
+        else
+                US_DEBUGP("Soft reset done\n");
+        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;
+}
diff --git a/drivers/usb/storage/transport.h b/drivers/usb/storage/transport.h
index e25f8d8fc741..8d9e0663f8fe 100644
--- a/drivers/usb/storage/transport.h
+++ b/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