linux-kernel - [PATCH 4/6] bdi: Use irqsave variant of refcount_dec_and

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Date:   Tue,  3 Jul 2018 22:01:39 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de, Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Anna-Maria Gleixner <anna-maria@...utronix.de>,
        linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 4/6] bdi: Use irqsave variant of refcount_dec_and_lock()

From: Anna-Maria Gleixner <anna-maria@...utronix.de>

The irqsave variant of refcount_dec_and_lock handles irqsave/restore when
taking/releasing the spin lock. With this variant the call of
local_irq_save/restore is no longer required.

Cc: linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Anna-Maria Gleixner <anna-maria@...utronix.de>
[bigeasy: s@...mic_dec_and_lock@...count_dec_and_lock@g ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 mm/backing-dev.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 55a233d75f39..f5981e9d6ae2 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -473,11 +473,8 @@ void wb_congested_put(struct bdi_writeback_congested *congested)
 {
 	unsigned long flags;
 
-	local_irq_save(flags);
-	if (!refcount_dec_and_lock(&congested->refcnt, &cgwb_lock)) {
-		local_irq_restore(flags);
+	if (!refcount_dec_and_lock_irqsave(&congested->refcnt, &cgwb_lock, &flags))
 		return;
-	}
 
 	/* bdi might already have been destroyed leaving @congested unlinked */
 	if (congested->__bdi) {
-- 
2.18.0