1 #ifndef __LINUX_LOCKREF_H
2 #define __LINUX_LOCKREF_H
5 * Locked reference counts.
7 * These are different from just plain atomic refcounts in that they
8 * are atomic with respect to the spinlock that goes with them. In
9 * particular, there can be implementations that don't actually get
10 * the spinlock for the common decrement/increment operations, but they
11 * still have to check that the operation is done semantically as if
12 * the spinlock had been taken (using a cmpxchg operation that covers
13 * both the lock and the count word, or using memory transactions, for
17 #include <linux/spinlock.h>
25 * lockref_get - Increments reference count unconditionally
26 * @lockcnt: pointer to lockref structure
28 * This operation is only valid if you already hold a reference
29 * to the object, so you know the count cannot be zero.
31 static inline void lockref_get(struct lockref *lockref)
33 spin_lock(&lockref->lock);
35 spin_unlock(&lockref->lock);
39 * lockref_get_not_zero - Increments count unless the count is 0
40 * @lockcnt: pointer to lockref structure
41 * Return: 1 if count updated successfully or 0 if count is 0
43 static inline int lockref_get_not_zero(struct lockref *lockref)
47 spin_lock(&lockref->lock);
52 spin_unlock(&lockref->lock);
57 * lockref_put_or_lock - decrements count unless count <= 1 before decrement
58 * @lockcnt: pointer to lockref structure
59 * Return: 1 if count updated successfully or 0 if count <= 1 and lock taken
61 static inline int lockref_put_or_lock(struct lockref *lockref)
63 spin_lock(&lockref->lock);
64 if (lockref->count <= 1)
67 spin_unlock(&lockref->lock);
71 #endif /* __LINUX_LOCKREF_H */