[PATCH] USB: add ability for usb-serial drivers to determine if their write...

[PATCH] USB: add ability for usb-serial drivers to determine if their write urb is currently being used.

This removes a lot of racy and buggy code by trying to check the status of the urb.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/cyberjack.c

@@ -213,10 +213,14 @@ static int cyberjack_write (struct usb_serial_port *port, const unsigned char *b
 		return (0);
 	}
 
-	if (port->write_urb->status == -EINPROGRESS) {
+	spin_lock(&port->lock);
+	if (port->write_urb_busy) {
+		spin_unlock(&port->lock);
 		dbg("%s - already writing", __FUNCTION__);
-		return (0);
+		return 0;
 	}
+	port->write_urb_busy = 1;
+	spin_unlock(&port->lock);
 
 	spin_lock_irqsave(&priv->lock, flags);
 
@@ -224,6 +228,7 @@ static int cyberjack_write (struct usb_serial_port *port, const unsigned char *b
 		/* To much data for buffer. Reset buffer. */
 		priv->wrfilled=0;
 		spin_unlock_irqrestore(&priv->lock, flags);
+		port->write_urb_busy = 0;
 		return (0);
 	}
 
@@ -268,6 +273,7 @@ static int cyberjack_write (struct usb_serial_port *port, const unsigned char *b
 			priv->wrfilled=0;
 			priv->wrsent=0;
 			spin_unlock_irqrestore(&priv->lock, flags);
+			port->write_urb_busy = 0;
 			return 0;
 		}
 
@@ -413,6 +419,7 @@ static void cyberjack_write_bulk_callback (struct urb *urb, struct pt_regs *regs
 
 	dbg("%s - port %d", __FUNCTION__, port->number);
 
+	port->write_urb_busy = 0;
 	if (urb->status) {
 		dbg("%s - nonzero write bulk status received: %d", __FUNCTION__, urb->status);
 		return;
@@ -424,12 +431,6 @@ static void cyberjack_write_bulk_callback (struct urb *urb, struct pt_regs *regs
 	if( priv->wrfilled ) {
 		int length, blksize, result;
 
-		if (port->write_urb->status == -EINPROGRESS) {
-			dbg("%s - already writing", __FUNCTION__);
-			spin_unlock(&priv->lock);
-			return;
-		}
-
 		dbg("%s - transmitting data (frame n)", __FUNCTION__);
 
 		length = ((priv->wrfilled - priv->wrsent) > port->bulk_out_size) ?

drivers/usb/serial/generic.c

@@ -174,10 +174,14 @@ int usb_serial_generic_write(struct usb_serial_port *port, const unsigned char *
 
 	/* only do something if we have a bulk out endpoint */
 	if (serial->num_bulk_out) {
-		if (port->write_urb->status == -EINPROGRESS) {
+		spin_lock(&port->lock);
+		if (port->write_urb_busy) {
+			spin_unlock(&port->lock);
 			dbg("%s - already writing", __FUNCTION__);
-			return (0);
+			return 0;
 		}
+		port->write_urb_busy = 1;
+		spin_unlock(&port->lock);
 
 		count = (count > port->bulk_out_size) ? port->bulk_out_size : count;
 
@@ -195,17 +199,20 @@ int usb_serial_generic_write(struct usb_serial_port *port, const unsigned char *
 				     usb_serial_generic_write_bulk_callback), port);
 
 		/* send the data out the bulk port */
+		port->write_urb_busy = 1;
 		result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
-		if (result)
+		if (result) {
 			dev_err(&port->dev, "%s - failed submitting write urb, error %d\n", __FUNCTION__, result);
-		else
+			/* don't have to grab the lock here, as we will retry if != 0 */
+			port->write_urb_busy = 0;
+		} else
 			result = count;
 
 		return result;
 	}
 
 	/* no bulk out, so return 0 bytes written */
-	return (0);
+	return 0;
 }
 
 int usb_serial_generic_write_room (struct usb_serial_port *port)
@@ -216,7 +223,7 @@ int usb_serial_generic_write_room (struct usb_serial_port *port)
 	dbg("%s - port %d", __FUNCTION__, port->number);
 
 	if (serial->num_bulk_out) {
-		if (port->write_urb->status != -EINPROGRESS)
+		if (port->write_urb_busy)
 			room = port->bulk_out_size;
 	}
 
@@ -232,7 +239,7 @@ int usb_serial_generic_chars_in_buffer (struct usb_serial_port *port)
 	dbg("%s - port %d", __FUNCTION__, port->number);
 
 	if (serial->num_bulk_out) {
-		if (port->write_urb->status == -EINPROGRESS)
+		if (port->write_urb_busy)
 			chars = port->write_urb->transfer_buffer_length;
 	}
 
@@ -291,6 +298,7 @@ void usb_serial_generic_write_bulk_callback (struct urb *urb, struct pt_regs *re
 
 	dbg("%s - port %d", __FUNCTION__, port->number);
 
+	port->write_urb_busy = 0;
 	if (urb->status) {
 		dbg("%s - nonzero write bulk status received: %d", __FUNCTION__, urb->status);
 		return;

drivers/usb/serial/ipaq.c

@@ -818,11 +818,6 @@ static void ipaq_write_gather(struct usb_serial_port *port)
 	struct ipaq_packet	*pkt, *tmp;
 	struct urb		*urb = port->write_urb;
 
-	if (urb->status == -EINPROGRESS) {
-		/* Should never happen */
-		err("%s - flushing while urb is active !", __FUNCTION__);
-		return;
-	}
 	room = URBDATA_SIZE;
 	list_for_each_entry_safe(pkt, tmp, &priv->queue, list) {
 		count = min(room, (int)(pkt->len - pkt->written));

drivers/usb/serial/ipw.c

@@ -400,9 +400,14 @@ static int ipw_write(struct usb_serial_port *port, const unsigned char *buf, int
 		return 0;
 	}
 
-	/* Racy and broken, FIXME properly! */
-	if (port->write_urb->status == -EINPROGRESS)
+	spin_lock(&port->lock);
+	if (port->write_urb_busy) {
+		spin_unlock(&port->lock);
+		dbg("%s - already writing", __FUNCTION__);
 		return 0;
+	}
+	port->write_urb_busy = 1;
+	spin_unlock(&port->lock);
 
 	count = min(count, port->bulk_out_size);
 	memcpy(port->bulk_out_buffer, buf, count);
@@ -418,6 +423,7 @@ static int ipw_write(struct usb_serial_port *port, const unsigned char *buf, int
 
 	ret = usb_submit_urb(port->write_urb, GFP_ATOMIC);
 	if (ret != 0) {
+		port->write_urb_busy = 0;
 		dbg("%s - usb_submit_urb(write bulk) failed with error = %d", __FUNCTION__, ret);
 		return ret;
 	}

drivers/usb/serial/ir-usb.c

@@ -341,10 +341,14 @@ static int ir_write (struct usb_serial_port *port, const unsigned char *buf, int
 	if (count == 0)
 		return 0;
 
-	if (port->write_urb->status == -EINPROGRESS) {
-		dbg ("%s - already writing", __FUNCTION__);
+	spin_lock(&port->lock);
+	if (port->write_urb_busy) {
+		spin_unlock(&port->lock);
+		dbg("%s - already writing", __FUNCTION__);
 		return 0;
 	}
+	port->write_urb_busy = 1;
+	spin_unlock(&port->lock);
 
 	transfer_buffer = port->write_urb->transfer_buffer;
 	transfer_size = min(count, port->bulk_out_size - 1);
@@ -374,9 +378,10 @@ static int ir_write (struct usb_serial_port *port, const unsigned char *buf, int
 	port->write_urb->transfer_flags = URB_ZERO_PACKET;
 
 	result = usb_submit_urb (port->write_urb, GFP_ATOMIC);
-	if (result)
+	if (result) {
+		port->write_urb_busy = 0;
 		dev_err(&port->dev, "%s - failed submitting write urb, error %d\n", __FUNCTION__, result);
-	else
+	} else
 		result = transfer_size;
 
 	return result;
@@ -388,6 +393,7 @@ static void ir_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
 
 	dbg("%s - port %d", __FUNCTION__, port->number);
 
+	port->write_urb_busy = 0;
 	if (urb->status) {
 		dbg("%s - nonzero write bulk status received: %d", __FUNCTION__, urb->status);
 		return;

drivers/usb/serial/keyspan_pda.c

@@ -520,9 +520,13 @@ static int keyspan_pda_write(struct usb_serial_port *port,
 	   the TX urb is in-flight (wait until it completes)
 	   the device is full (wait until it says there is room)
 	*/
-	if (port->write_urb->status == -EINPROGRESS || priv->tx_throttled ) {
-		return( 0 );
+	spin_lock(&port->lock);
+	if (port->write_urb_busy || priv->tx_throttled) {
+		spin_unlock(&port->lock);
+		return 0;
 	}
+	port->write_urb_busy = 1;
+	spin_unlock(&port->lock);
 
 	/* At this point the URB is in our control, nobody else can submit it
 	   again (the only sudden transition was the one from EINPROGRESS to
@@ -593,6 +597,8 @@ static int keyspan_pda_write(struct usb_serial_port *port,
 
 	rc = count;
 exit:
+	if (rc < 0)
+		port->write_urb_busy = 0;
 	return rc;
 }
 
@@ -602,6 +608,7 @@ static void keyspan_pda_write_bulk_callback (struct urb *urb, struct pt_regs *re
 	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
 	struct keyspan_pda_private *priv;
 
+	port->write_urb_busy = 0;
 	priv = usb_get_serial_port_data(port);
 
 	/* queue up a wakeup at scheduler time */
@@ -631,7 +638,7 @@ static int keyspan_pda_chars_in_buffer (struct usb_serial_port *port)
 
 	/* when throttled, return at least WAKEUP_CHARS to tell select() (via
 	   n_tty.c:normal_poll() ) that we're not writeable. */
-	if( port->write_urb->status == -EINPROGRESS || priv->tx_throttled )
+	if (port->write_urb_busy || priv->tx_throttled)
 		return 256;
 	return 0;
 }

drivers/usb/serial/omninet.c

@@ -254,10 +254,15 @@ static int omninet_write (struct usb_serial_port *port, const unsigned char *buf
 		dbg("%s - write request of 0 bytes", __FUNCTION__);
 		return (0);
 	}
-	if (wport->write_urb->status == -EINPROGRESS) {
+
+	spin_lock(&port->lock);
+	if (port->write_urb_busy) {
+		spin_unlock(&port->lock);
 		dbg("%s - already writing", __FUNCTION__);
-		return (0);
+		return 0;
 	}
+	port->write_urb_busy = 1;
+	spin_unlock(&port->lock);
 
 	count = (count > OMNINET_BULKOUTSIZE) ? OMNINET_BULKOUTSIZE : count;
 
@@ -275,9 +280,10 @@ static int omninet_write (struct usb_serial_port *port, const unsigned char *buf
 
 	wport->write_urb->dev = serial->dev;
 	result = usb_submit_urb(wport->write_urb, GFP_ATOMIC);
-	if (result)
+	if (result) {
+		port->write_urb_busy = 0;
 		err("%s - failed submitting write urb, error %d", __FUNCTION__, result);
-	else
+	} else
 		result = count;
 
 	return result;
@@ -291,7 +297,7 @@ static int omninet_write_room (struct usb_serial_port *port)
 
 	int room = 0; // Default: no room
 
-	if (wport->write_urb->status != -EINPROGRESS)
+	if (wport->write_urb_busy)
 		room = wport->bulk_out_size - OMNINET_HEADERLEN;
 
 //	dbg("omninet_write_room returns %d", room);
@@ -306,6 +312,7 @@ static void omninet_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
 
 //	dbg("omninet_write_bulk_callback, port %0x\n", port);
 
+	port->write_urb_busy = 0;
 	if (urb->status) {
 		dbg("%s - nonzero write bulk status received: %d", __FUNCTION__, urb->status);
 		return;

drivers/usb/serial/safe_serial.c

@@ -299,10 +299,14 @@ static int safe_write (struct usb_serial_port *port, const unsigned char *buf, i
 		dbg ("%s - write request of 0 bytes", __FUNCTION__);
 		return (0);
 	}
-	if (port->write_urb->status == -EINPROGRESS) {
-		dbg ("%s - already writing", __FUNCTION__);
-		return (0);
+	spin_lock(&port->lock);
+	if (port->write_urb_busy) {
+		spin_unlock(&port->lock);
+		dbg("%s - already writing", __FUNCTION__);
+		return 0;
 	}
+	port->write_urb_busy = 1;
+	spin_unlock(&port->lock);
 
 	packet_length = port->bulk_out_size;	// get max packetsize
 
@@ -354,6 +358,7 @@ static int safe_write (struct usb_serial_port *port, const unsigned char *buf, i
 #endif
 	port->write_urb->dev = port->serial->dev;
 	if ((result = usb_submit_urb (port->write_urb, GFP_KERNEL))) {
+		port->write_urb_busy = 0;
 		err ("%s - failed submitting write urb, error %d", __FUNCTION__, result);
 		return 0;
 	}
@@ -368,7 +373,7 @@ static int safe_write_room (struct usb_serial_port *port)
 
 	dbg ("%s", __FUNCTION__);
 
-	if (port->write_urb->status != -EINPROGRESS)
+	if (port->write_urb_busy)
 		room = port->bulk_out_size - (safe ? 2 : 0);
 
 	if (room) {

drivers/usb/serial/usb-serial.c

@@ -1047,6 +1047,7 @@ int usb_serial_probe(struct usb_interface *interface,
 		memset(port, 0x00, sizeof(struct usb_serial_port));
 		port->number = i + serial->minor;
 		port->serial = serial;
+		spin_lock_init(&port->lock);
 		INIT_WORK(&port->work, usb_serial_port_softint, port);
 		serial->port[i] = port;
 	}

drivers/usb/serial/usb-serial.h

@@ -69,6 +69,7 @@
  * usb_serial_port: structure for the specific ports of a device.
  * @serial: pointer back to the struct usb_serial owner of this port.
  * @tty: pointer to the corresponding tty for this port.
+ * @lock: spinlock to grab when updating portions of this structure.
  * @number: the number of the port (the minor number).
  * @interrupt_in_buffer: pointer to the interrupt in buffer for this port.
  * @interrupt_in_urb: pointer to the interrupt in struct urb for this port.
@@ -98,6 +99,7 @@
 struct usb_serial_port {
 	struct usb_serial *	serial;
 	struct tty_struct *	tty;
+	spinlock_t		lock;
 	unsigned char		number;
 
 	unsigned char *		interrupt_in_buffer;
@@ -117,6 +119,7 @@ struct usb_serial_port {
 	unsigned char *		bulk_out_buffer;
 	int			bulk_out_size;
 	struct urb *		write_urb;
+	int			write_urb_busy;
 	__u8			bulk_out_endpointAddress;
 
 	wait_queue_head_t	write_wait;