linux-kernel - [tip:perf/core] perf/x86: Remove warning for zero PEBS status

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Date:	Wed, 6 Jan 2016 10:50:30 -0800
From:	tip-bot for Andi Kleen <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	peterz@...radead.org, acme@...hat.com, jolsa@...hat.com,
	linux-kernel@...r.kernel.org, eranian@...gle.com, mingo@...nel.org,
	ak@...ux.intel.com, vincent.weaver@...ne.edu, hpa@...or.com,
	torvalds@...ux-foundation.org, tglx@...utronix.de
Subject: [tip:perf/core] perf/x86: Remove warning for zero PEBS status

Commit-ID:  957ea1fdbcdb909e1540f06f06f1a9ce6e696efa
Gitweb:     http://git.kernel.org/tip/957ea1fdbcdb909e1540f06f06f1a9ce6e696efa
Author:     Andi Kleen <ak@...ux.intel.com>
AuthorDate: Thu, 3 Dec 2015 13:22:19 -0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 6 Jan 2016 11:15:30 +0100

perf/x86: Remove warning for zero PEBS status

The recent commit:

  75f80859b130 ("perf/x86/intel/pebs: Robustify PEBS buffer drain")

causes lots of warnings on different CPUs before Skylake
when running PEBS intensive workloads.

They can have a zero status field in the PEBS record when
PEBS is racing with clearing of GLOBAl_STATUS.

This also can cause hangs (it seems there are still
problems with printk in NMI).

Disable the warning, but still ignore the record.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Link: http://lkml.kernel.org/r/1449177740-5422-1-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/perf_event_intel_ds.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 5db1c77..0e3a9c7 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -1232,10 +1232,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
 
 		bit = find_first_bit((unsigned long *)&pebs_status,
 					x86_pmu.max_pebs_events);
-		if (WARN(bit >= x86_pmu.max_pebs_events,
-			 "PEBS record without PEBS event! status=%Lx pebs_enabled=%Lx active_mask=%Lx",
-			 (unsigned long long)p->status, (unsigned long long)cpuc->pebs_enabled,
-			 *(unsigned long long *)cpuc->active_mask))
+		if (bit >= x86_pmu.max_pebs_events)
 			continue;
 
 		/*
--
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