From b58af4066d240b18b43f202e07b9ec7461d90b17 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 4 Aug 2010 15:45:57 +0200 Subject: USB: serial: fix stalled writes As David VomLehn points out, it was possible to receive an interrupt before clearing the free-urb flag which could lead to the urb being incorrectly marked as busy. For the same reason, move tx_bytes accounting so that it will never be negative. Note that the free-flags set and clear operations do not need any additional locking as they are manipulated while USB_SERIAL_WRITE_BUSY is set. Reported-by: David VomLehn Tested-by: David VomLehn Signed-off-by: Johan Hovold Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/generic.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c index a817ced82835..ca92f67747cc 100644 --- a/drivers/usb/serial/generic.c +++ b/drivers/usb/serial/generic.c @@ -208,18 +208,23 @@ retry: urb->transfer_buffer_length = count; usb_serial_debug_data(debug, &port->dev, __func__, count, urb->transfer_buffer); + spin_lock_irqsave(&port->lock, flags); + port->tx_bytes += count; + spin_unlock_irqrestore(&port->lock, flags); + + clear_bit(i, &port->write_urbs_free); result = usb_submit_urb(urb, GFP_ATOMIC); if (result) { dev_err(&port->dev, "%s - error submitting urb: %d\n", __func__, result); + set_bit(i, &port->write_urbs_free); + spin_lock_irqsave(&port->lock, flags); + port->tx_bytes -= count; + spin_unlock_irqrestore(&port->lock, flags); + clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags); return result; } - clear_bit(i, &port->write_urbs_free); - - spin_lock_irqsave(&port->lock, flags); - port->tx_bytes += count; - spin_unlock_irqrestore(&port->lock, flags); /* Try sending off another urb, unless in irq context (in which case * there will be no free urb). */ -- cgit v1.2.3