linux-kernel - [tip:perf/urgent] perf/x86/ibs: Fix IBS throttle

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Message-ID: <tip-0158b83f7508851cda9e62c4b14678c5bd492cb2@git.kernel.org>
Date:	Mon, 21 Mar 2016 02:49:02 -0700
From:	tip-bot for Peter Zijlstra <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	acme@...hat.com, jolsa@...hat.com, peterz@...radead.org,
	namhyung@...nel.org, vince@...ter.net, luto@...capital.net,
	bp@...en8.de, hpa@...or.com, mingo@...nel.org, dsahern@...il.com,
	eranian@...gle.com, torvalds@...ux-foundation.org,
	vincent.weaver@...ne.edu, dvlasenk@...hat.com, brgerst@...il.com,
	tglx@...utronix.de, alexander.shishkin@...ux.intel.com,
	linux-kernel@...r.kernel.org
Subject: [tip:perf/urgent] perf/x86/ibs: Fix IBS throttle

Commit-ID:  0158b83f7508851cda9e62c4b14678c5bd492cb2
Gitweb:     http://git.kernel.org/tip/0158b83f7508851cda9e62c4b14678c5bd492cb2
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Fri, 11 Mar 2016 15:23:46 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 21 Mar 2016 09:08:15 +0100

perf/x86/ibs: Fix IBS throttle

When the IBS IRQ handler get a !0 return from perf_event_overflow;
meaning it should throttle the event, it only disables it, it doesn't
call perf_ibs_stop().

This confuses the state machine, as we'll use pmu::start() ->
perf_ibs_start() to unthrottle.

Tested-by: Borislav Petkov <bp@...en8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Brian Gerst <brgerst@...il.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vince Weaver <vince@...ter.net>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Cc: dvyukov@...gle.com
Cc: oleg@...hat.com
Cc: panand@...hat.com
Cc: sasha.levin@...cle.com
Link: http://lkml.kernel.org/r/20160311142346.GE6344@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/events/amd/ibs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index 51087c2..7956d29 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -599,7 +599,7 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
 	throttle = perf_event_overflow(event, &data, &regs);
 out:
 	if (throttle)
-		perf_ibs_disable_event(perf_ibs, hwc, *config);
+		perf_ibs_stop(event, 0);
 	else
 		perf_ibs_enable_event(perf_ibs, hwc, period >> 4);