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locking/refcounts: Implement refcount_dec_and_lock_irqsave()

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There are in-tree users of refcount_dec_and_lock() which must acquire the
spin lock with interrupts disabled. To workaround the lack of an irqsave
variant of refcount_dec_and_lock() they use local_irq_save() at the call
site. This causes extra code and creates in some places unneeded long
interrupt disabled times. These places need also extra treatment for
PREEMPT_RT due to the disconnect of the irq disabling and the lock
function.

Implement the missing irqsave variant of the function.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r20180612161621.22645-4-bigeasy@linutronix.de

[bigeasy: s@atomic_dec_and_lock@refcount_dec_and_lock@g]
This commit is contained in:
Anna-Maria Gleixner
2018-06-12 18:16:21 +02:00
committed by Thomas Gleixner
parent ccfbb5bed4
commit 7ea959c457
2 changed files with 31 additions and 1 deletions
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4
include/linux/refcount.h
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@@ -98,5 +98,7 @@ extern __must_check bool refcount_dec_if_one(refcount_t *r);
extern __must_check bool refcount_dec_not_one(refcount_t *r);
extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock);
extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock);
extern __must_check bool refcount_dec_and_lock_irqsave(refcount_t *r,
spinlock_t *lock,
unsigned long *flags);
#endif /* _LINUX_REFCOUNT_H */