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Message-ID: <20230720094555.1397621-6-chengming.zhou@linux.dev>
Date: Thu, 20 Jul 2023 17:45:54 +0800
From: chengming.zhou@...ux.dev
To: axboe@...nel.dk, osandov@...com, ming.lei@...hat.com,
kbusch@...nel.org, krisman@...e.de
Cc: linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
zhouchengming@...edance.com
Subject: [PATCH 5/6] sbitmap: wake_index doesn't need to be atomic_t
From: Chengming Zhou <zhouchengming@...edance.com>
We use wake_index to remember from which to wake up next time, which
doesn't need to be atomic_t since we only read it once before wakeups,
and write it once after wakeups.
Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
---
include/linux/sbitmap.h | 2 +-
lib/sbitmap.c | 12 ++++++------
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h
index d662cf136021..bdbe478ba4dc 100644
--- a/include/linux/sbitmap.h
+++ b/include/linux/sbitmap.h
@@ -116,7 +116,7 @@ struct sbitmap_queue {
/**
* @wake_index: Next wait queue in @ws to wake up.
*/
- atomic_t wake_index;
+ unsigned int wake_index;
/**
* @ws: Wait queues.
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 50bdf3a31947..6778ab3fc6a5 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -419,7 +419,7 @@ int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
sbq->min_shallow_depth = UINT_MAX;
sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
- atomic_set(&sbq->wake_index, 0);
+ sbq->wake_index = 0;
atomic_set(&sbq->ws_active, 0);
atomic_set(&sbq->completion_cnt, 0);
atomic_set(&sbq->wakeup_cnt, 0);
@@ -549,7 +549,7 @@ static void __sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)
if (!atomic_read(&sbq->ws_active))
return;
- wake_index = atomic_read(&sbq->wake_index);
+ wake_index = READ_ONCE(sbq->wake_index);
for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
struct sbq_wait_state *ws = &sbq->ws[wake_index];
@@ -570,8 +570,8 @@ static void __sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)
break;
}
- if (wake_index != atomic_read(&sbq->wake_index))
- atomic_set(&sbq->wake_index, wake_index);
+ if (wake_index != READ_ONCE(sbq->wake_index))
+ WRITE_ONCE(sbq->wake_index, wake_index);
}
void sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)
@@ -672,7 +672,7 @@ void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
* sbitmap_queue_wake_up().
*/
smp_mb();
- wake_index = atomic_read(&sbq->wake_index);
+ wake_index = READ_ONCE(sbq->wake_index);
for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
struct sbq_wait_state *ws = &sbq->ws[wake_index];
@@ -702,7 +702,7 @@ void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m)
seq_puts(m, "}\n");
seq_printf(m, "wake_batch=%u\n", sbq->wake_batch);
- seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index));
+ seq_printf(m, "wake_index=%d\n", READ_ONCE(sbq->wake_index));
seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active));
seq_puts(m, "ws={\n");
--
2.41.0
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