linux-kernel - Re: [PATCH 1/3] perf/x86/intel: Factor out common code of PMI handler

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Message-ID: <3b2e234a-0c09-2c36-b555-54f3b9fd1e35@linux.intel.com>
Date:   Tue, 7 Aug 2018 11:29:01 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     tglx@...utronix.de, mingo@...hat.com, acme@...nel.org,
        linux-kernel@...r.kernel.org, eranian@...gle.com,
        ak@...ux.intel.com, alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH 1/3] perf/x86/intel: Factor out common code of PMI handler



On 8/6/2018 2:20 PM, Peter Zijlstra wrote:
> On Mon, Aug 06, 2018 at 10:23:41AM -0700, kan.liang@...ux.intel.com wrote:
>> +	if (++loops > 100) {
>> +		static bool warned;
>> +
>> +		if (!warned) {
>> +			WARN(1, "perfevents: irq loop stuck!\n");
>> +			perf_event_print_debug();
>> +			warned = true;
>> +		}
> 
> Bah, that really reads like we want WARN_ONCE(), except for that
> perf_event_print_debug() thing :/
> 

Yes. I went though the log. To make the WARN text pair with 
perf_event_print_debug(), we open-coded WARN_ONCE()'s
one-time-only logic here since commit ae0def05ed85 ("perf/x86: Only 
print PMU state when also WARN()'ing")

I think I will still keep the logic here and just fix the complaint from 
checkpatch.pl.

Thanks,
Kan