linux-kernel - Re: [PATCH] perf/x86/uncore: Allow single pmu/box within events group

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Message-ID: <20161118112850.GO3117@twins.programming.kicks-ass.net>
Date:   Fri, 18 Nov 2016 12:28:50 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     "Liang, Kan" <kan.liang@...el.com>,
        Andi Kleen <andi@...stfloor.org>,
        Vince Weaver <vince@...ter.net>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] perf/x86/uncore: Allow single pmu/box within events group

On Fri, Nov 18, 2016 at 01:15:28AM +0100, Jiri Olsa wrote:
> Current uncore_validate_group code expects all events within
> the group to have same pmu.
> 
> This leads to constraint code using wrong boxes which leads
> in my case to touching uninitialized spinlocks, but could
> be probably worse.. depends on type and box details.
> 
> I get lockdep warning below for following perf stat:
>   # perf stat -vv -e '{uncore_cbox_0/config=0x0334/,uncore_qpi_0/event=1/}' -a sleep 1

Hurm, we shouldn't be allowing that in the first place I think.


Let me stare at the generic group code, the intent was to only allow
software events to mix with hw events, nothing else.