From: Johan Hovold <johan@kernel.org> [ Upstream commit dd5619582d60007139f0447382d2839f4f9e339b ] TIOCSSERIAL is a horrid, underspecified, legacy interface which for most serial devices is only useful for setting the close_delay and closing_wait parameters. A non-privileged user has only ever been able to set the since long deprecated ASYNC_SPD flags and trying to change any other *supported* feature should result in -EPERM being returned. Setting the current values for any supported features should return success. Fix the cdc-acm implementation which instead indicated that the TIOCSSERIAL ioctl was not even implemented when a non-privileged user set the current values. Fixes: ba2d8ce9db0a ("cdc-acm: implement TIOCSSERIAL to avoid blocking close(2)") Acked-by: Oliver Neukum <oneukum@suse.com> Signed-off-by: Johan Hovold <johan@kernel.org> Link: https://lore.kernel.org/r/20210408131602.27956-3-johan@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- drivers/usb/class/cdc-acm.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 7f4f21ba8efcf..738de8c9c354b 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -987,8 +987,6 @@ static int set_serial_info(struct acm *acm, if ((new_serial.close_delay != old_close_delay) || (new_serial.closing_wait != old_closing_wait)) retval = -EPERM; - else - retval = -EOPNOTSUPP; } else { acm->port.close_delay = close_delay; acm->port.closing_wait = closing_wait; -- 2.25.1