Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline CPUs

From: Michael Ellerman
Date: Tue Feb 09 2016 - 04:24:56 EST


On Fri, 2016-02-05 at 09:36 -0500, Steven Rostedt wrote:
> On Fri, 5 Feb 2016 14:20:17 +0300
> Denis Kirjanov <kda@xxxxxxxxxxxxxxxxx> wrote:
> > > > > Signed-off-by: Denis Kirjanov <kda@xxxxxxxxxxxxxxxxx>
> > >
> > > Hi Steven,
> > >
> > > please apply with Michael's acked-by tag.
> >
> > ping
>
> Actually, can you take this through the ppc tree? The
> TRACE_EVENT_FN_COND is already in mainline.
>
> You can add my:
>
> Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

Thanks, will do.

I tidied up the change log a bit:

powerpc/pseries: Don't trace hcalls on offline CPUs

If a cpu is hotplugged while the hcall trace points are active, it's
possible to hit a warning from RCU due to the trace points calling into
RCU from an offline cpu, eg:

RCU used illegally from offline CPU!
rcu_scheduler_active = 1, debug_locks = 1

Make the hypervisor tracepoints conditional by using
TRACE_EVENT_FN_COND.

Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Denis Kirjanov <kda@xxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>


cheers