Re: [PATCH] clocksource/drivers/ti-32k: Prevent ftrace recursion

Jisheng Zhang
2016-09-23T02:09:26Z

Hi Thomas,

On Thu, 22 Sep 2016 15:58:03 +0200 Thomas Gleixner wrote:

> On Thu, 22 Sep 2016, Jisheng Zhang wrote:
>
> > Currently ti-32k can be used as a scheduler clock. We properly marked
> > omap_32k_read_sched_clock() as notrace but we then call another
> > function ti_32k_read_cycles() that _wasn't_ notrace.
> >
> > Having a traceable function in the sched_clock() path leads to a
> > recursion within ftrace and a kernel crash.
>
> Kernel crash? Doesn't ftrace core prevent recursion?

a recent similar issue:

http://www.spinics.net/lists/arm-kernel/msg533480.html

Thanks,
Jisheng