[PATCH] USB Storage: remove dependency on SCSI-provided serial/tag number

This patch started life as as531 from Alan Stern.  It has been rediffed
against the latest tree.

The SCSI people have deprecated the use of scsi_cmnd.serial_number for
anything other than printk.  Worse than that, the SCSI core doesn't
always increment the number (when the error handler is running, for
example).  So this patch creates a locally-stored value for use in
bulk-only tags.  The net result is a simplification, since we no longer
have to save & restore the serial_number value while autosensing.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NMatthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/storage/transport.c

@@ -611,7 +611,6 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 		unsigned char old_sc_data_direction;
 		unsigned char old_cmd_len;
 		unsigned char old_cmnd[MAX_COMMAND_SIZE];
-		unsigned long old_serial_number;
 		int old_resid;
 
 		US_DEBUGP("Issuing auto-REQUEST_SENSE\n");
@@ -648,10 +647,6 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 		old_sg = srb->use_sg;
 		srb->use_sg = 0;
 
-		/* change the serial number -- toggle the high bit*/
-		old_serial_number = srb->serial_number;
-		srb->serial_number ^= 0x80000000;
-
 		/* issue the auto-sense command */
 		old_resid = srb->resid;
 		srb->resid = 0;
@@ -662,7 +657,6 @@ void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
 		srb->request_buffer = old_request_buffer;
 		srb->request_bufflen = old_request_bufflen;
 		srb->use_sg = old_sg;
-		srb->serial_number = old_serial_number;
 		srb->sc_data_direction = old_sc_data_direction;
 		srb->cmd_len = old_cmd_len;
 		memcpy(srb->cmnd, old_cmnd, MAX_COMMAND_SIZE);
@@ -985,7 +979,7 @@ int usb_stor_Bulk_transport(struct scsi_cmnd *srb, struct us_data *us)
 	bcb->Signature = cpu_to_le32(US_BULK_CB_SIGN);
 	bcb->DataTransferLength = cpu_to_le32(transfer_length);
 	bcb->Flags = srb->sc_data_direction == DMA_FROM_DEVICE ? 1 << 7 : 0;
-	bcb->Tag = srb->serial_number;
+	bcb->Tag = ++us->tag;
 	bcb->Lun = srb->device->lun;
 	if (us->flags & US_FL_SCM_MULT_TARG)
 		bcb->Lun |= srb->device->id << 4;
@@ -1074,7 +1068,7 @@ int usb_stor_Bulk_transport(struct scsi_cmnd *srb, struct us_data *us)
 	US_DEBUGP("Bulk Status S 0x%x T 0x%x R %u Stat 0x%x\n",
 			le32_to_cpu(bcs->Signature), bcs->Tag, 
 			residue, bcs->Status);
-	if (bcs->Tag != srb->serial_number || bcs->Status > US_BULK_STAT_PHASE) {
+	if (bcs->Tag != us->tag || bcs->Status > US_BULK_STAT_PHASE) {
 		US_DEBUGP("Bulk logical error\n");
 		return USB_STOR_TRANSPORT_ERROR;
 	}

drivers/usb/storage/usb.h

@@ -158,6 +158,7 @@ struct us_data {
 
 	/* SCSI interfaces */
 	struct scsi_cmnd	*srb;		 /* current srb		*/
+	unsigned int		tag;		 /* current dCBWTag	*/
 
 	/* thread information */
 	int			pid;		 /* control thread	 */