linux-kernel - [PATCH V4 3/8] perf/x86/intel/uncore: correct fixed counter index check in generic code

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Date:   Thu,  2 Nov 2017 13:29:48 -0700
From:   kan.liang@...el.com
To:     tglx@...utronix.de, peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     acme@...nel.org, eranian@...gle.com, ak@...ux.intel.com,
        Kan Liang <Kan.liang@...el.com>
Subject: [PATCH V4 3/8] perf/x86/intel/uncore: correct fixed counter index check in generic code

From: Kan Liang <Kan.liang@...el.com>

There is no index which is bigger than UNCORE_PMC_IDX_FIXED. The only
exception is client IMC uncore. It has customized function to deal with
the 'UNCORE_PMC_IDX_FIXED + 1' case. It does not touch the generic code.
For generic code, it is not correct to use >= to check fixed counter.
The code quality issue will bring problem when new counter index is
introduced.

Signed-off-by: Kan Liang <Kan.liang@...el.com>
---

Changes since V3:
 - Split the patch for generic change

 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 1c5390f..3b8cd88 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);
-- 
2.7.4