linux-kernel - [PATCH 2/4] block/part_stat: use __this_cpu_add() instead of access by smp_processor

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Date:   Mon, 04 May 2020 16:29:32 +0300
From:   Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 2/4] block/part_stat: use __this_cpu_add() instead of access
 by smp_processor_id()

Most architectures have fast path to access percpu for current cpu.
Required preempt_disable() is provided by part_stat_lock().

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
---
 include/linux/part_stat.h |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/include/linux/part_stat.h b/include/linux/part_stat.h
index 755a01f0fd61..a0ddeff3798e 100644
--- a/include/linux/part_stat.h
+++ b/include/linux/part_stat.h
@@ -36,6 +36,9 @@
 	res;								\
 })
 
+#define __part_stat_add(part, field, addnd)				\
+	__this_cpu_add((part)->dkstats->field, addnd)
+
 static inline void part_stat_set_all(struct hd_struct *part, int value)
 {
 	int i;
@@ -64,6 +67,9 @@ static inline void free_part_stats(struct hd_struct *part)
 #define part_stat_get_cpu(part, field, cpu)	part_stat_get(part, field)
 #define part_stat_read(part, field)		part_stat_get(part, field)
 
+#define __part_stat_add(part, field, addnd)				\
+	(part_stat_get(part, field) += (addnd))
+
 static inline void part_stat_set_all(struct hd_struct *part, int value)
 {
 	memset(&part->dkstats, value, sizeof(struct disk_stats));
@@ -85,9 +91,6 @@ static inline void free_part_stats(struct hd_struct *part)
 	 part_stat_read(part, field[STAT_WRITE]) +			\
 	 part_stat_read(part, field[STAT_DISCARD]))
 
-#define __part_stat_add(part, field, addnd)				\
-	(part_stat_get(part, field) += (addnd))
-
 #define part_stat_add(part, field, addnd)	do {			\
 	__part_stat_add((part), field, addnd);				\
 	if ((part)->partno)						\