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

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Message-Id: <20180703200141.28415-7-bigeasy@linutronix.de>
Date:   Tue,  3 Jul 2018 22:01:41 +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>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 6/6] userns: 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: 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>
---
 kernel/user.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/user.c b/kernel/user.c
index 5f65ef195259..0df9b1640b2a 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -169,11 +169,8 @@ void free_uid(struct user_struct *up)
 	if (!up)
 		return;
 
-	local_irq_save(flags);
-	if (refcount_dec_and_lock(&up->__count, &uidhash_lock))
+	if (refcount_dec_and_lock_irqsave(&up->__count, &uidhash_lock, &flags))
 		free_user(up, flags);
-	else
-		local_irq_restore(flags);
 }
 
 struct user_struct *alloc_uid(kuid_t uid)
-- 
2.18.0