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On 08/11/12 19:47, Dan Williams wrote:
> 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@xxxxxxxxxx> Cc:
> stable@xxxxxxxxxxxxxxx
Works pretty well for me.
Tested-by: Aleksander Morgado <aleksander@xxxxxxx>
> --- drivers/usb/class/cdc-acm.c | 38
> ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38
> insertions(+)
>
> diff --git a/drivers/usb/class/cdc-acm.c
> b/drivers/usb/class/cdc-acm.c index 6e49ec6..8d809a8 100644 ---
> a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@
> -787,6 +787,10 @@ static int get_serial_info(struct acm *acm,
> struct serial_struct __user *info) tmp.flags = ASYNC_LOW_LATENCY;
> tmp.xmit_fifo_size = acm->writesize; tmp.baud_base =
> le32_to_cpu(acm->line.dwDTERate); + tmp.close_delay =
> acm->port.close_delay / 10; + tmp.closing_wait =
> acm->port.closing_wait == ASYNC_CLOSING_WAIT_NONE ? +
> ASYNC_CLOSING_WAIT_NONE : + acm->port.closing_wait / 10;
>
> if (copy_to_user(info, &tmp, sizeof(tmp))) return -EFAULT; @@
> -794,6 +798,37 @@ static int get_serial_info(struct acm *acm,
> struct serial_struct __user *info) return 0; }
>
> +static int set_serial_info(struct acm *acm, + struct
> serial_struct __user *newinfo) +{ + struct serial_struct
> new_serial; + unsigned int closing_wait, close_delay; + int retval
> = 0; + + if (copy_from_user(&new_serial, newinfo,
> sizeof(new_serial))) + return -EFAULT; + + close_delay =
> new_serial.close_delay * 10; + closing_wait =
> new_serial.closing_wait == ASYNC_CLOSING_WAIT_NONE ? +
> ASYNC_CLOSING_WAIT_NONE : new_serial.closing_wait * 10; + +
> mutex_lock(&acm->port.mutex); + + if (!capable(CAP_SYS_ADMIN)) { +
> if ((close_delay != acm->port.close_delay) || + (closing_wait
> != acm->port.closing_wait)) + retval = -EPERM; + else + retval
> = -EOPNOTSUPP; + } else { + acm->port.close_delay = close_delay;
> + acm->port.closing_wait = closing_wait; + } + +
> mutex_unlock(&acm->port.mutex); + return retval; +} + static int
> acm_tty_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned
> long arg) { @@ -804,6 +839,9 @@ static int acm_tty_ioctl(struct
> tty_struct *tty, case TIOCGSERIAL: /* gets serial port data */ rv =
> get_serial_info(acm, (struct serial_struct __user *) arg); break; +
> case TIOCSSERIAL: + rv = set_serial_info(acm, (struct
> serial_struct __user *) arg); + break; }
>
> return rv;
>
- --
Aleksander
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