mirror of https://gitee.com/openkylin/linux.git
70 lines
1.7 KiB
C
70 lines
1.7 KiB
C
#include <linux/export.h>
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#include <linux/lockref.h>
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/**
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* lockref_get - Increments reference count unconditionally
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* @lockcnt: pointer to lockref structure
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*
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* This operation is only valid if you already hold a reference
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* to the object, so you know the count cannot be zero.
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*/
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void lockref_get(struct lockref *lockref)
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{
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spin_lock(&lockref->lock);
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lockref->count++;
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spin_unlock(&lockref->lock);
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}
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EXPORT_SYMBOL(lockref_get);
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/**
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* lockref_get_not_zero - Increments count unless the count is 0
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* @lockcnt: pointer to lockref structure
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* Return: 1 if count updated successfully or 0 if count was zero
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*/
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int lockref_get_not_zero(struct lockref *lockref)
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{
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int retval = 0;
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spin_lock(&lockref->lock);
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if (lockref->count) {
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lockref->count++;
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retval = 1;
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}
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spin_unlock(&lockref->lock);
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return retval;
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}
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EXPORT_SYMBOL(lockref_get_not_zero);
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/**
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* lockref_get_or_lock - Increments count unless the count is 0
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* @lockcnt: pointer to lockref structure
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* Return: 1 if count updated successfully or 0 if count was zero
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* and we got the lock instead.
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*/
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int lockref_get_or_lock(struct lockref *lockref)
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{
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spin_lock(&lockref->lock);
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if (!lockref->count)
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return 0;
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lockref->count++;
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spin_unlock(&lockref->lock);
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return 1;
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}
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EXPORT_SYMBOL(lockref_get_or_lock);
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/**
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* lockref_put_or_lock - decrements count unless count <= 1 before decrement
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* @lockcnt: pointer to lockref structure
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* Return: 1 if count updated successfully or 0 if count <= 1 and lock taken
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*/
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int lockref_put_or_lock(struct lockref *lockref)
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{
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spin_lock(&lockref->lock);
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if (lockref->count <= 1)
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return 0;
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lockref->count--;
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spin_unlock(&lockref->lock);
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return 1;
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}
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EXPORT_SYMBOL(lockref_put_or_lock);
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