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

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Message-ID: <1455009881.13384.1.camel@ellerman.id.au>
Date:	Tue, 09 Feb 2016 20:24:41 +1100
From:	Michael Ellerman <mpe@...erman.id.au>
To:	Steven Rostedt <rostedt@...dmis.org>,
	Denis Kirjanov <kda@...ux-powerpc.org>
Cc:	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline
 CPUs

On Fri, 2016-02-05 at 09:36 -0500, Steven Rostedt wrote:
> On Fri, 5 Feb 2016 14:20:17 +0300
> Denis Kirjanov <kda@...ux-powerpc.org> wrote:
> > > > > Signed-off-by: Denis Kirjanov <kda@...ux-powerpc.org>
> > >
> > > 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@...dmis.org>

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@...dmis.org>
    Signed-off-by: Denis Kirjanov <kda@...ux-powerpc.org>
    Signed-off-by: Michael Ellerman <mpe@...erman.id.au>


cheers