linux-kernel - Re: [PATCH] gpiolib: fix line event timestamps for nested irqs

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Date:   Fri, 11 Jan 2019 14:45:08 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH] gpiolib: fix line event timestamps for nested irqs

pt., 11 sty 2019 o 13:19 Linus Walleij <linus.walleij@...aro.org> napisał(a):
>
> On Fri, Jan 4, 2019 at 11:32 AM Bartosz Golaszewski <brgl@...ev.pl> wrote:
>
> > From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> >
> > Nested interrupts run inside the calling thread's context and the top
> > half handler is never called which means that we never read the
> > timestamp.
> >
> > This issue came up when trying to read line events from a gpiochip
> > using regmap_irq_chip for interrupts.
> >
> > Fix it by reading the timestamp from the irq thread function if it's
> > still 0 by the time the second handler is called.
> >
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
>
> Oh that's right. Should this not have Fixes: and Cc: stable?
>
> > +       /*
> > +        * We may be running from a nested threaded interrupt in which case
> > +        * we didn't get the timestamp from lineevent_irq_handler().
> > +        */
> > +       if (!le->timestamp)
> > +               le->timestamp = ktime_get_real_ns();
> > +
> >         ge.timestamp = le->timestamp;
>
> I would merge these:
>
> if (!le->timestamp)
>     ge.timestamp = ktime_get_real_ns();
> else
>     ge.timestamp = le->timestamp;
>
> Yours,
> Linus Walleij

I'll fix both issues and resend.

Bart