linux-kernel - [tip:perf/core] perf/x86/intel/uncore: Correct fixed counter index check in generic code

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Message-ID: <tip-4749f8196452eeb73cf2086a6a9705bae479d33d@git.kernel.org>
Date:   Thu, 31 May 2018 05:31:04 -0700
From:   tip-bot for Kan Liang <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, linux-kernel@...r.kernel.org, hpa@...or.com,
        peterz@...radead.org, kan.liang@...el.com, tglx@...utronix.de,
        torvalds@...ux-foundation.org
Subject: [tip:perf/core] perf/x86/intel/uncore: Correct fixed counter index
 check in generic code

Commit-ID:  4749f8196452eeb73cf2086a6a9705bae479d33d
Gitweb:     https://git.kernel.org/tip/4749f8196452eeb73cf2086a6a9705bae479d33d
Author:     Kan Liang <kan.liang@...el.com>
AuthorDate: Thu, 3 May 2018 11:25:08 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 31 May 2018 12:36:28 +0200

perf/x86/intel/uncore: Correct fixed counter index check in generic code

There is no index which is bigger than UNCORE_PMC_IDX_FIXED. The only
exception is client IMC uncore, which has been specially handled.
For generic code, it is not correct to use >= to check fixed counter.
The code quality issue will bring problem when a new counter index is
introduced.

Signed-off-by: Kan Liang <kan.liang@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: acme@...nel.org
Cc: eranian@...gle.com
Link: http://lkml.kernel.org/r/1525371913-10597-3-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/events/intel/uncore.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index a7956fc7ca1d..3b0f93eb3cc0 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -218,7 +218,7 @@ void uncore_perf_event_update(struct intel_uncore_box *box, struct perf_event *e
 	u64 prev_count, new_count, delta;
 	int shift;
 
-	if (event->hw.idx >= UNCORE_PMC_IDX_FIXED)
+	if (event->hw.idx == UNCORE_PMC_IDX_FIXED)
 		shift = 64 - uncore_fixed_ctr_bits(box);
 	else
 		shift = 64 - uncore_perf_ctr_bits(box);