cdc-acm: implement TIOCSSERIAL to avoid blocking close(2)
authorDan Williams <dcbw@redhat.com>
Thu, 8 Nov 2012 18:47:41 +0000 (12:47 -0600)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 17 Dec 2012 18:37:46 +0000 (10:37 -0800)
commit1229a83d1ea3d11b4433f7080825d05044af45a9
treec75a1e4fc8d0c962c16ad0f31a31e64f698a16dc
parent455d8953951baf0d38673b010100241e508b765c
cdc-acm: implement TIOCSSERIAL to avoid blocking close(2)

commit ba2d8ce9db0a61505362bb17b8899df3d3326146 upstream.

Some devices (ex Nokia C7) simply don't respond at all when data is sent
to some of their USB interfaces.  The data gets stuck in the TTYs queue
and sits there until close(2), which them blocks because closing_wait
defaults to 30 seconds (even though the fd is O_NONBLOCK).  This is
rarely desired.  Implement the standard mechanism to adjust closing_wait
and let applications handle it how they want to.

See also 02303f73373aa1da19dbec510ec5a4e2576f9610 for usb_wwan.c.

Signed-off-by: Dan Williams <dcbw@redhat.com>
Acked-by: Oliver Neukum <oneukum@suse.de>
Tested-by: Aleksander Morgado <aleksander@gnu.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/class/cdc-acm.c