linux-kernel - [PATCH 3/7] aio: remove no longer needed preempt

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Date:	Fri, 15 Aug 2014 13:24:49 -0400
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-aio@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/7] aio: remove no longer needed preempt_disable()

Based on feedback from Jens Axboe on 263782c1c95bbddbb022dc092fd89a36bb8d5577,
clean up get/put_reqs_available() to remove the no longer needed preempt_disable()
and preempt_enable() pair.

Signed-off-by: Benjamin LaHaise <bcrl@...ck.org>
Cc: Jens Axboe <axboe@...nel.dk>
---
 fs/aio.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 8216aa0..9ce9e8e 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -814,10 +814,8 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
 	struct kioctx_cpu *kcpu;
 	unsigned long flags;
 
-	preempt_disable();
-	kcpu = this_cpu_ptr(ctx->cpu);
-
 	local_irq_save(flags);
+	kcpu = this_cpu_ptr(ctx->cpu);
 	kcpu->reqs_available += nr;
 
 	while (kcpu->reqs_available >= ctx->req_batch * 2) {
@@ -826,7 +824,6 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
 	}
 
 	local_irq_restore(flags);
-	preempt_enable();
 }
 
 static bool get_reqs_available(struct kioctx *ctx)
@@ -835,10 +832,8 @@ static bool get_reqs_available(struct kioctx *ctx)
 	bool ret = false;
 	unsigned long flags;
 
-	preempt_disable();
-	kcpu = this_cpu_ptr(ctx->cpu);
-
 	local_irq_save(flags);
+	kcpu = this_cpu_ptr(ctx->cpu);
 	if (!kcpu->reqs_available) {
 		int old, avail = atomic_read(&ctx->reqs_available);
 
@@ -858,7 +853,6 @@ static bool get_reqs_available(struct kioctx *ctx)
 	kcpu->reqs_available--;
 out:
 	local_irq_restore(flags);
-	preempt_enable();
 	return ret;
 }
 
-- 
1.8.2.1


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