diff options
| author | Johan Hovold <jhovold@gmail.com> | 2010-08-04 15:45:57 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-13 13:31:01 -0700 |
| commit | 4a561f2ed8e6e5c428bae18af3f48045211add08 (patch) | |
| tree | f94ecea674295ce62a6c0908d6724c469004a9c9 | |
| parent | 8762dc2878fcdab3a3d71502c42e5923c79e8086 (diff) | |
USB: serial: fix stalled writes
commit b58af4066d240b18b43f202e07b9ec7461d90b17 upstream.
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 <dvomlehn@cisco.com>
Tested-by: David VomLehn <dvomlehn@cisco.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/usb/serial/generic.c | 15 |
1 files 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). */ |