linux-kernel - Re: [PATCH v7 3/3] leds: trigger: implement a tty trigger

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Message-ID: <20200713102600.ts672o72krjky5gi@pengutronix.de>
Date:   Mon, 13 Jul 2020 12:26:00 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Pavel Machek <pavel@...x.de>
Cc:     kernel@...gutronix.de,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        linux-serial@...r.kernel.org, Jiri Slaby <jslaby@...e.com>,
        linux-leds@...r.kernel.org, Dan Murphy <dmurphy@...com>
Subject: Re: [PATCH v7 3/3] leds: trigger: implement a tty trigger

Hello Pavel,

On Sun, Jul 12, 2020 at 10:24:53AM +0200, Pavel Machek wrote:
> > +++ b/drivers/leds/trigger/ledtrig-tty.c
> > @@ -0,0 +1,192 @@
> > +// SPDX-License-Identifier: GPL-2.0
> 
> 2.0+ is preffered.

My employer requests GPL-2.0-only for kernel code.

> > +	while (firstrun ||
> > +	       icount.rx != trigger_data->rx ||
> > +	       icount.tx != trigger_data->tx) {
> > +
> > +		led_set_brightness(trigger_data->led_cdev, LED_ON);
> > +
> > +		msleep(100);
> > +
> > +		led_set_brightness(trigger_data->led_cdev, LED_OFF);
> 
> Is this good idea inside workqueue?

What is "this"? The msleep? Calling led_set_brightness? What would you
recommend instead? Maybe led_set_brightness_nosleep()?

> > +		trigger_data->rx = icount.rx;
> > +		trigger_data->tx = icount.tx;
> > +		firstrun = false;
> > +
> > +		ret = tty_get_icount(trigger_data->tty, &icount);
> > +		if (ret)
> > +			return;
> 
> Unbalanced locking.

indeed, will fix and resend after the above issues are resolved.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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