Johan Hovold af7414836d USB: serial: keyspan_pda: fix write unthrottling
commit 320f9028c7873c3c7710e8e93e5c979f4c857490 upstream.

The driver did not update its view of the available device buffer space
until write() was called in task context. This meant that write_room()
would return 0 even after the device had sent a write-unthrottle
notification, something which could lead to blocked writers not being
woken up (e.g. when using OPOST).

Note that we must also request an unthrottle notification is case a
write() request fills the device buffer exactly.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-30 11:51:37 +01:00
..
2019-09-03 19:00:39 +02:00
2019-09-02 19:20:57 +02:00