[PATCH] USB: Patch to prevent overlapping access by usb-storage and usbfs

usb: Based on a 2.4 patch from John_Hull@Dell.com, this patch
     serializes usb storage and usbfs operation, so that usbfs
     cannot disturb storage by seemingly harmless control reads.
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/usb/storage/isd200.c

@@ -485,7 +485,9 @@ static int isd200_action( struct us_data *us, int action,
 
 	memcpy(srb->cmnd, &ata, sizeof(ata.generic));
 	srb->cmd_len = sizeof(ata.generic);
+	down(&(us->pusb_dev->serialize));
 	status = usb_stor_Bulk_transport(srb, us);
+	up(&(us->pusb_dev->serialize));
 	if (status == USB_STOR_TRANSPORT_GOOD)
 		status = ISD200_GOOD;
 	else {
@@ -545,7 +547,9 @@ static void isd200_invoke_transport( struct us_data *us,
 	/* send the command to the transport layer */
 	memcpy(srb->cmnd, ataCdb, sizeof(ataCdb->generic));
 	srb->cmd_len = sizeof(ataCdb->generic);
+	down(&(us->pusb_dev->serialize));
 	transferStatus = usb_stor_Bulk_transport(srb, us);
+	up(&(us->pusb_dev->serialize));
 
 	/* if the command gets aborted by the higher layers, we need to
 	 * short-circuit all other processing

drivers/usb/storage/transport.c

@@ -527,9 +527,18 @@ void usb_stor_invoke_transport(Scsi_Cmnd *srb, struct us_data *us)
 	int need_auto_sense;
 	int result;
 
+	/*
+	 * Grab device's serialize mutex to prevent /usbfs and others from
+	 * sending out a command in the middle of ours (if libusb sends a
+	 * get_descriptor or something on pipe 0 after our CBW and before
+	 * our CSW, and then we get a stall, we have trouble)
+	 */
+ 
 	/* send the command to the transport layer */
+	down(&(us->pusb_dev->serialize));
 	srb->resid = 0;
 	result = us->transport(srb, us);
+	up(&(us->pusb_dev->serialize));
 
 	/* if the command gets aborted by the higher layers, we need to
 	 * short-circuit all other processing
@@ -648,9 +657,11 @@ void usb_stor_invoke_transport(Scsi_Cmnd *srb, struct us_data *us)
 		srb->serial_number ^= 0x80000000;
 
 		/* issue the auto-sense command */
+		down(&(us->pusb_dev->serialize));
 		old_resid = srb->resid;
 		srb->resid = 0;
 		temp_result = us->transport(us->srb, us);
+		up(&(us->pusb_dev->serialize));
 
 		/* let's clean up right away */
 		srb->resid = old_resid;