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

From: Thomas Gleixner
Date: Thu Sep 22 2016 - 10:00:34 EST


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?

Thanks,

tglx