From: Doug Anderson <dianders@chromium.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <swboyd@chromium.org>,
John Stultz <john.stultz@linaro.org>,
Ravi Chandra Sadineni <ravisadineni@chromium.org>,
LKML <linux-kernel@vger.kernel.org>,
Stephen Boyd <sboyd@kernel.org>
Subject: Re: [PATCH 2/4] alarmtimer: Make alarmtimer platform device child of RTC device
Date: Wed, 15 Jan 2020 11:22:26 -0800 [thread overview]
Message-ID: <CAD=FV=XDPyJJEzjQTd8=6Om0i0HYRfin1+X5Feqcdu5oM0Ro+g@mail.gmail.com> (raw)
In-Reply-To: <87v9pdxcc2.fsf@nanos.tec.linutronix.de>
Hi,
On Wed, Jan 15, 2020 at 2:07 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> Doug Anderson <dianders@chromium.org> writes:
> > On Thu, Jan 9, 2020 at 7:59 AM Stephen Boyd <swboyd@chromium.org> wrote:
> >> diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
> >> index 4b11f0309eee..ccb6aea4f1d4 100644
> >> --- a/kernel/time/alarmtimer.c
> >> +++ b/kernel/time/alarmtimer.c
> >> @@ -88,6 +88,7 @@ static int alarmtimer_rtc_add_device(struct device *dev,
> >> unsigned long flags;
> >> struct rtc_device *rtc = to_rtc_device(dev);
> >> struct wakeup_source *__ws;
> >> + struct platform_device *pdev;
> >> int ret = 0;
> >>
> >> if (rtcdev)
> >> @@ -99,6 +100,7 @@ static int alarmtimer_rtc_add_device(struct device *dev,
> >> return -1;
> >>
> >> __ws = wakeup_source_register(dev, "alarmtimer");
> >> + pdev = platform_device_register_data(dev, "alarmtimer", -1, NULL, 0);
> >
> > Don't you need to check for an error here? If pdev is an error you'll
> > continue on your merry way. Before your patch if you got an error
> > registering the device it would have caused probe to fail.
>
> Yes, that return value should be checked
>
> > I guess you'd only want it to be an error if "rtcdev" is NULL?
>
> If rtcdev is not NULL then this code is not reached. See the begin of
> this function :)
Wow, not sure how I missed that. I guess the one at the top of the
function is an optimization, though? It's being accessed without the
spinlock which means that it's not necessarily reliable, right? I
guess once the rtcdev has been set then it is never unset, but it does
seem like if two threads could call alarmtimer_rtc_add_device() at the
same time then it's possible that we could end up calling
wakeup_source_register() for both of them. Did I understand that
correctly? If I did then maybe it deserves a comment?
-Doug
next prev parent reply other threads:[~2020-01-15 19:22 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-09 15:59 [PATCH 0/4] Fix alarmtimer suspend failure Stephen Boyd
2020-01-09 15:59 ` [PATCH 1/4] alarmtimer: Unregister wakeup source when module get fails Stephen Boyd
2020-01-15 3:40 ` Doug Anderson
2020-01-15 10:24 ` [tip: timers/core] " tip-bot2 for Stephen Boyd
2020-01-09 15:59 ` [PATCH 2/4] alarmtimer: Make alarmtimer platform device child of RTC device Stephen Boyd
2020-01-15 3:40 ` Doug Anderson
2020-01-15 10:07 ` Thomas Gleixner
2020-01-15 16:47 ` Stephen Boyd
2020-01-15 19:32 ` Doug Anderson
2020-01-15 19:22 ` Doug Anderson [this message]
2020-01-17 1:25 ` Stephen Boyd
2020-01-09 15:59 ` [PATCH 3/4] alarmtimer: Use wakeup source from alarmtimer platform device Stephen Boyd
2020-01-15 19:47 ` Doug Anderson
2020-01-09 15:59 ` [PATCH 4/4] alarmtimer: Always export alarmtimer_get_rtcdev() and update docs Stephen Boyd
2020-01-15 20:31 ` Doug Anderson
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