linux-kernel - Re: [PATCH] perf/bts: Don't try handling BTS interrupt if BTS is not enabled

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Message-ID: <CAB7JpEFP8-=7xpWxjraQK8-VPHoaq2Fd6z4i51WrvaZfAyu2Ow@mail.gmail.com>
Date:   Tue, 27 Sep 2016 00:05:29 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>, bp@...e.de,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf/bts: Don't try handling BTS interrupt if BTS is not enabled

http://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?id=f1e1c9e5e357c05253affb13be29285c5cb56bf0

On 26 September 2016 at 22:19, Boris Ostrovsky
<boris.ostrovsky@...cle.com> wrote:
> Otherwise we will try to dereference ds which has not been allocated.
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> ---
>  arch/x86/events/intel/bts.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
> index bdcd651..1f5657f 100644
> --- a/arch/x86/events/intel/bts.c
> +++ b/arch/x86/events/intel/bts.c
> @@ -451,6 +451,9 @@ int intel_bts_interrupt(void)
>         s64 old_head;
>         int err = -ENOSPC, handled = 0;
>
> +       if (!x86_pmu.bts)
> +               return 0;
> +
>         /*
>          * The only surefire way of knowing if this NMI is ours is by checking
>          * the write ptr against the PMI threshold.
> --
> 1.8.3.1
>