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#include <linux/module.h>

#include <linux/spinlock.h>

#include <asm/atomic.h>

/*

 * This is an architecture-neutral, but slow,

 * implementation of the notion of "decrement

 * a reference count, and return locked if it

 * decremented to zero".

 *

 * NOTE NOTE NOTE! This is _not_ equivalent to

 *

 *      if (atomic_dec_and_test(&atomic)) {

 *              spin_lock(&lock);

 *              return 1;

 *      }

 *      return 0;

 *

 * because the spin-lock and the decrement must be

 * "atomic".

 *

 * This slow version gets the spinlock unconditionally,

 * and releases it if it isn't needed. Architectures

 * are encouraged to come up with better approaches,

 * this is trivially done efficiently using a load-locked

 * store-conditional approach, for example.

 */

#ifndef ATOMIC_DEC_AND_LOCK

int atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)

{

        spin_lock(lock);

        if (atomic_dec_and_test(atomic))

                return 1;

        spin_unlock(lock);

        return 0;

}

EXPORT_SYMBOL(atomic_dec_and_lock);

#endif