From: jszhang@marvell.com (Jisheng Zhang)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] clocksource/drivers/ti-32k: Prevent ftrace recursion
Date: Fri, 23 Sep 2016 10:48:29 +0800 [thread overview]
Message-ID: <20160923104829.29a3b68b@xhacker> (raw)
In-Reply-To: <20160922224514.696ae61b@gandalf.local.home>
On Thu, 22 Sep 2016 22:45:14 -0400 Steven Rostedt wrote:
> On Fri, 23 Sep 2016 10:04:31 +0800
> Jisheng Zhang <jszhang@marvell.com> wrote:
>
> > 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
>
> Right. But Thomas brought up recursion detection. And I said that would
> be the fix, but now thinking about it, I've updated the recursion
> protection so that timer issues should not cause a crash.
>
Got it. Thanks for the clarification
prev parent reply other threads:[~2016-09-23 2:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-22 7:56 [PATCH] clocksource/drivers/ti-32k: Prevent ftrace recursion Jisheng Zhang
2016-09-22 13:58 ` Thomas Gleixner
2016-09-22 14:29 ` Steven Rostedt
2016-09-23 2:04 ` Jisheng Zhang
2016-09-23 2:45 ` Steven Rostedt
2016-09-23 2:48 ` Jisheng Zhang [this message]
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