linux-imx

// SPDX-License-Identifier: GPL-2.0

#include <linux/export.h>

#include <linux/lockref.h>

​

#if USE_CMPXCHG_LOCKREF

​

/*

 * Note that the "cmpxchg()" reloads the "old" value for the

 * failure case.

 */

#define CMPXCHG_LOOP(CODE, SUCCESS) do {                    \

    struct lockref old;                         \

    BUILD_BUG_ON(sizeof(old) != 8);                     \

    old.lock_count = READ_ONCE(lockref->lock_count);            \

    while (likely(arch_spin_value_unlocked(old.lock.rlock.raw_lock))) {     \

        struct lockref new = old, prev = old;               \

        CODE                                \

        old.lock_count = cmpxchg64_relaxed(&lockref->lock_count,    \

                           old.lock_count,      \

                           new.lock_count);     \

        if (likely(old.lock_count == prev.lock_count)) {        \

            SUCCESS;                        \

        }                               \

        cpu_relax();                            \

    }                                   \

} while (0)

​

#else

​

#define CMPXCHG_LOOP(CODE, SUCCESS) do { } while (0)

​

#endif

​

/**

 * lockref_get - Increments reference count unconditionally

 * @lockref: pointer to lockref structure

 *

 * This operation is only valid if you already hold a reference

 * to the object, so you know the count cannot be zero.

 */

void lockref_get(struct lockref *lockref)

{

    CMPXCHG_LOOP(

        new.count++;

    ,

        return;

    );

​

    spin_lock(&lockref->lock);

    lockref->count++;

    spin_unlock(&lockref->lock);

}

EXPORT_SYMBOL(lockref_get);

​

/**

 * lockref_get_not_zero - Increments count unless the count is 0 or dead

 * @lockref: pointer to lockref structure

 * Return: 1 if count updated successfully or 0 if count was zero

 */

int lockref_get_not_zero(struct lockref *lockref)

{

    int retval;

​