1 #include <linux/export.h> 2 #include <linux/lockref.h> 3 4 /** 5 * lockref_get - Increments reference count unconditionally 6 * @lockcnt: pointer to lockref structure 7 * 8 * This operation is only valid if you already hold a reference 9 * to the object, so you know the count cannot be zero. 10 */ 11 void lockref_get(struct lockref *lockref) 12 { 13 spin_lock(&lockref->lock); 14 lockref->count++; 15 spin_unlock(&lockref->lock); 16 } 17 EXPORT_SYMBOL(lockref_get); 18 19 /** 20 * lockref_get_not_zero - Increments count unless the count is 0 21 * @lockcnt: pointer to lockref structure 22 * Return: 1 if count updated successfully or 0 if count was zero 23 */ 24 int lockref_get_not_zero(struct lockref *lockref) 25 { 26 int retval = 0; 27 28 spin_lock(&lockref->lock); 29 if (lockref->count) { 30 lockref->count++; 31 retval = 1; 32 } 33 spin_unlock(&lockref->lock); 34 return retval; 35 } 36 EXPORT_SYMBOL(lockref_get_not_zero); 37 38 /** 39 * lockref_get_or_lock - Increments count unless the count is 0 40 * @lockcnt: pointer to lockref structure 41 * Return: 1 if count updated successfully or 0 if count was zero 42 * and we got the lock instead. 43 */ 44 int lockref_get_or_lock(struct lockref *lockref) 45 { 46 spin_lock(&lockref->lock); 47 if (!lockref->count) 48 return 0; 49 lockref->count++; 50 spin_unlock(&lockref->lock); 51 return 1; 52 } 53 EXPORT_SYMBOL(lockref_get_or_lock); 54 55 /** 56 * lockref_put_or_lock - decrements count unless count <= 1 before decrement 57 * @lockcnt: pointer to lockref structure 58 * Return: 1 if count updated successfully or 0 if count <= 1 and lock taken 59 */ 60 int lockref_put_or_lock(struct lockref *lockref) 61 { 62 spin_lock(&lockref->lock); 63 if (lockref->count <= 1) 64 return 0; 65 lockref->count--; 66 spin_unlock(&lockref->lock); 67 return 1; 68 } 69 EXPORT_SYMBOL(lockref_put_or_lock); 70