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

From: tip-bot for Peter Zijlstra
Date: Mon Mar 21 2016 - 05:53:08 EST

Commit-ID: 0158b83f7508851cda9e62c4b14678c5bd492cb2
Gitweb: http://git.kernel.org/tip/0158b83f7508851cda9e62c4b14678c5bd492cb2
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 11 Mar 2016 15:23:46 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vince@xxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Cc: dvyukov@xxxxxxxxxx
Cc: oleg@xxxxxxxxxx
Cc: panand@xxxxxxxxxx
Cc: sasha.levin@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20160311142346.GE6344@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
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);
if (throttle)
- perf_ibs_disable_event(perf_ibs, hwc, *config);
+ perf_ibs_stop(event, 0);
perf_ibs_enable_event(perf_ibs, hwc, period >> 4);