Re: [PATCH] clocksource: timer-ti-dm: Fix regression

Frank Lee
2020-01-07T19:14:59Z

On Tue, Jan 7, 2020 at 5:07 AM Olof Johansson <olof@lixom.net> wrote:
>
> On Mon, Jan 6, 2020 at 12:37 PM Tony Lindgren <tony@atomide.com> wrote:
> >
> > Clean-up commit 8c82723414d5 ("clocksource/drivers/timer-ti-dm: Switch to
> > platform_get_irq") caused a regression where we now try to access
> > uninitialized data for timer:
> >
> > drivers/clocksource/timer-ti-dm.c: In function 'omap_dm_timer_probe':
> > drivers/clocksource/timer-ti-dm.c:798:13: warning: 'timer' may be used
> > uninitialized in this function [-Wmaybe-uninitialized]
> >
> > On boot we now get:
> >
> > Unable to handle kernel NULL pointer dereference at virtual address
> > 00000004
> > ...
> > (omap_dm_timer_probe) from [<c061ac7c>] (platform_drv_probe+0x48/0x98)
> > (platform_drv_probe) from [<c0618c04>] (really_probe+0x1dc/0x348)
> > (really_probe) from [<c0618ef4>] (driver_probe_device+0x5c/0x160)
> >
> > Let's fix the issue by moving platform_get_irq to happen after timer has
> > been allocated.
> >
> > Fixes: 8c82723414d5 ("clocksource/drivers/timer-ti-dm: Switch to platform_get_irq")
> > Cc: Yangtao Li <tiny.windzz@gmail.com>
> > Signed-off-by: Tony Lindgren <tony@atomide.com>
>
> Acked-by: Olof Johansson <olof@lixom.net>

Acked-by: Yangtao Li <tiny.windzz@gmail.com>

I am sorry. I will pay attention next time.

>
> > ---
> >
> > I did not notice simlar issue with other patches in the series, but
> > please do double check Yangtao.
>
> Yeah, this even seems to be caught at build (but our builds have been
> so noisy with warnings lately that they're hard to spot):
>
> /build/drivers/clocksource/timer-ti-dm.c: In function 'omap_dm_timer_probe':
> /build/drivers/clocksource/timer-ti-dm.c:798:13: warning: 'timer' may
> be used uninitialized in this function [-Wmaybe-uninitialized]
> 798 | timer->irq = platform_get_irq(pdev, 0);
> | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> -Olof