Re: [PATCHv2] serio: add hangup support

[Hans Verkuil <hansverk@cisco.com>]

Hi Dmitry,

I don't know if you processed this patch yet, but if not, can you update a
small mistake in the commit log? See below.

On 08/03/16 17:26, Dmitry Torokhov wrote:
> On Wed, Aug 03, 2016 at 01:00:44PM +0200, Hans Verkuil wrote:
>> The Pulse-Eight USB CEC adapter is a usb device that shows up as a ttyACM0 device.
>> It requires that you run inputattach in order to communicate with it via serio.
>>
>> This all works well, but it would be nice to have a udev rule to automatically
>> start inputattach. That too works OK, but the problem comes when the USB device
>> is unplugged: the tty hangup is never handled by the serio framework so the
>> inputattach utility never exits and you have to kill it manually.
>>
>> By adding this hangup callback the inputattach utility now properly exits as
>> soon as the USB device is unplugged.
>>
>> The udev rule I used on my Debian sid system is:
>>
>> SUBSYSTEM=="tty", KERNEL=="ttyACM[0-9]*", ATTRS{idVendor}=="2548", ATTRS{idProduct}=="1002", ACTION=="add", TAG+="systemd", ENV{SYSTEMD_WANTS}+="pulse8-cec-inputattach@%k.service"
>>
>> And pulse8-cec-inputattach@%k.service is as follows:

^^^^ This line should read:

And /etc/systemd/system/pulse8-cec-inputattach@.service is as follows:

(I had a spurious %k in the name, and it didn't have the full path)

Regards,

	Hans

>>
>> ===============================================================
>> [Unit]
>> Description=inputattach for pulse8-cec device on %I
>>
>> [Service]
>> Type=simple
>> ExecStart=/usr/local/bin/inputattach --pulse8-cec /dev/%I
>> KillMode=process
>> ===============================================================
>>
>> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
>> Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
>> ---
>> Change since the original RFC patch: don't call close() from the hangup() function,
>> instead only set the DEAD flag in hangup() instead of in close().
>> ---
>> diff --git a/drivers/input/serio/serport.c b/drivers/input/serio/serport.c
>> index 9c927d3..4045e95 100644
>> --- a/drivers/input/serio/serport.c
>> +++ b/drivers/input/serio/serport.c
>> @@ -71,7 +71,6 @@ static void serport_serio_close(struct serio *serio)
>>
>>  	spin_lock_irqsave(&serport->lock, flags);
>>  	clear_bit(SERPORT_ACTIVE, &serport->flags);
>> -	set_bit(SERPORT_DEAD, &serport->flags);
>>  	spin_unlock_irqrestore(&serport->lock, flags);
>>
>>  	wake_up_interruptible(&serport->wait);
> 
> I think we should remove this line as well - the waiter is waiting on
> SERPORT_DEAD bit, if we are not setting it we do not need to wake up the
> waiter either.
> 
> I can fix it up on my side.
> 
>> @@ -248,6 +247,19 @@ static long serport_ldisc_compat_ioctl(struct tty_struct *tty,
>>  }
>>  #endif
>>
>> +static int serport_ldisc_hangup(struct tty_struct * tty)
>> +{
>> +	struct serport *serport = (struct serport *) tty->disc_data;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&serport->lock, flags);
>> +	set_bit(SERPORT_DEAD, &serport->flags);
>> +	spin_unlock_irqrestore(&serport->lock, flags);
>> +
>> +	wake_up_interruptible(&serport->wait);
>> +	return 0;
>> +}
>> +
>>  static void serport_ldisc_write_wakeup(struct tty_struct * tty)
>>  {
>>  	struct serport *serport = (struct serport *) tty->disc_data;
>> @@ -274,6 +286,7 @@ static struct tty_ldisc_ops serport_ldisc = {
>>  	.compat_ioctl =	serport_ldisc_compat_ioctl,
>>  #endif
>>  	.receive_buf =	serport_ldisc_receive,
>> +	.hangup =	serport_ldisc_hangup,
>>  	.write_wakeup =	serport_ldisc_write_wakeup
>>  };
>>
> 
> Thanks.
>