linux-kernel - [PATCH v12 03/10] perf/amd/iommu: Clean up perf_iommu

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Date:   Wed, 22 Mar 2017 02:02:35 -0500
From:   Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
To:     <linux-kernel@...r.kernel.org>, <iommu@...ts.linux-foundation.org>
CC:     <bp@...en8.de>, <peterz@...radead.org>, <joro@...tes.org>,
        <mingo@...hat.com>,
        Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [PATCH v12 03/10] perf/amd/iommu: Clean up perf_iommu_read()

Fix coding style and make use of GENMASK_ULL macro.

Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Joerg Roedel <joro@...tes.org>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 arch/x86/events/amd/iommu.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
index e112f49..d4375da 100644
--- a/arch/x86/events/amd/iommu.c
+++ b/arch/x86/events/amd/iommu.c
@@ -320,9 +320,7 @@ static void perf_iommu_start(struct perf_event *event, int flags)
 
 static void perf_iommu_read(struct perf_event *event)
 {
-	u64 count = 0ULL;
-	u64 prev_raw_count = 0ULL;
-	u64 delta = 0ULL;
+	u64 count, prev, delta;
 	struct hw_perf_event *hwc = &event->hw;
 
 	amd_iommu_pc_get_set_reg_val(_GET_DEVID(event),
@@ -330,18 +328,16 @@ static void perf_iommu_read(struct perf_event *event)
 				IOMMU_PC_COUNTER_REG, &count, false);
 
 	/* IOMMU pc counter register is only 48 bits */
-	count &= 0xFFFFFFFFFFFFULL;
+	count &= GENMASK_ULL(47, 0);
 
-	prev_raw_count =  local64_read(&hwc->prev_count);
-	if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
-					count) != prev_raw_count)
+	prev = local64_read(&hwc->prev_count);
+	if (local64_cmpxchg(&hwc->prev_count, prev, count) != prev)
 		return;
 
-	/* Handling 48-bit counter overflowing */
-	delta = (count << COUNTER_SHIFT) - (prev_raw_count << COUNTER_SHIFT);
+	/* Handle 48-bit counter overflow */
+	delta = (count << COUNTER_SHIFT) - (prev << COUNTER_SHIFT);
 	delta >>= COUNTER_SHIFT;
 	local64_add(delta, &event->count);
-
 }
 
 static void perf_iommu_stop(struct perf_event *event, int flags)
-- 
1.8.3.1