userns: use irqsave variant of refcount_dec_and_lock()

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.

[bigeasy@linutronix.de: s@atomic_dec_and_lock@refcount_dec_and_lock@g]
Link: http://lkml.kernel.org/r/20180703200141.28415-7-bigeasy@linutronix.de
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/user.c b/kernel/user.c
index 5f65ef1..0df9b16 100644 (file)
--- 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)