usb-storage: make use of srb local variable

Commit 8b52291a ("usb-storage: fix deadlock involving host lock
and scsi_done") added a local variable to usb_stor_control_thread() in
the usb-storage driver.  This local variable holds the value of
us->srb, for use after the host lock has been released.

But as long as we have the value in a local variable, we may as well
use it instead of dereferencing the us pointer all over the place.
This patch makes no functional change; it just makes the code a little
shorter and a little neater.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/storage/usb.c

@@ -332,7 +332,7 @@ static int usb_stor_control_thread(void * __us)
 
 		/* When we are called with no command pending, we're done */
 		srb = us->srb;
-		if (us->srb == NULL) {
+		if (srb == NULL) {
 			scsi_unlock(host);
 			mutex_unlock(&us->dev_mutex);
 			usb_stor_dbg(us, "-- exiting\n");
@@ -341,7 +341,7 @@ static int usb_stor_control_thread(void * __us)
 
 		/* has the command timed out *already* ? */
 		if (test_bit(US_FLIDX_TIMED_OUT, &us->dflags)) {
-			us->srb->result = DID_ABORT << 16;
+			srb->result = DID_ABORT << 16;
 			goto SkipForAbort;
 		}
 
@@ -351,35 +351,35 @@ static int usb_stor_control_thread(void * __us)
 		 * reject the command if the direction indicator
 		 * is UNKNOWN
 		 */
-		if (us->srb->sc_data_direction == DMA_BIDIRECTIONAL) {
+		if (srb->sc_data_direction == DMA_BIDIRECTIONAL) {
 			usb_stor_dbg(us, "UNKNOWN data direction\n");
-			us->srb->result = DID_ERROR << 16;
+			srb->result = DID_ERROR << 16;
 		}
 
 		/*
 		 * reject if target != 0 or if LUN is higher than
 		 * the maximum known LUN
 		 */
-		else if (us->srb->device->id &&
+		else if (srb->device->id &&
 				!(us->fflags & US_FL_SCM_MULT_TARG)) {
 			usb_stor_dbg(us, "Bad target number (%d:%llu)\n",
-				     us->srb->device->id,
-				     us->srb->device->lun);
-			us->srb->result = DID_BAD_TARGET << 16;
+				     srb->device->id,
+				     srb->device->lun);
+			srb->result = DID_BAD_TARGET << 16;
 		}
 
-		else if (us->srb->device->lun > us->max_lun) {
+		else if (srb->device->lun > us->max_lun) {
 			usb_stor_dbg(us, "Bad LUN (%d:%llu)\n",
-				     us->srb->device->id,
-				     us->srb->device->lun);
-			us->srb->result = DID_BAD_TARGET << 16;
+				     srb->device->id,
+				     srb->device->lun);
+			srb->result = DID_BAD_TARGET << 16;
 		}
 
 		/*
 		 * Handle those devices which need us to fake
 		 * their inquiry data
 		 */
-		else if ((us->srb->cmnd[0] == INQUIRY) &&
+		else if ((srb->cmnd[0] == INQUIRY) &&
 			    (us->fflags & US_FL_FIX_INQUIRY)) {
 			unsigned char data_ptr[36] = {
 			    0x00, 0x80, 0x02, 0x02,
@@ -387,13 +387,13 @@ static int usb_stor_control_thread(void * __us)
 
 			usb_stor_dbg(us, "Faking INQUIRY command\n");
 			fill_inquiry_response(us, data_ptr, 36);
-			us->srb->result = SAM_STAT_GOOD;
+			srb->result = SAM_STAT_GOOD;
 		}
 
 		/* we've got a command, let's do it! */
 		else {
-			US_DEBUG(usb_stor_show_command(us, us->srb));
-			us->proto_handler(us->srb, us);
+			US_DEBUG(usb_stor_show_command(us, srb));
+			us->proto_handler(srb, us);
 			usb_mark_last_busy(us->pusb_dev);
 		}
 
@@ -401,7 +401,7 @@ static int usb_stor_control_thread(void * __us)
 		scsi_lock(host);
 
 		/* was the command aborted? */
-		if (us->srb->result == DID_ABORT << 16) {
+		if (srb->result == DID_ABORT << 16) {
 SkipForAbort:
 			usb_stor_dbg(us, "scsi command aborted\n");
 			srb = NULL;	/* Don't call srb->scsi_done() */