Release 4.11 lib/dec_and_lock.c

#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>

/*
 * This is an 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".
 */


int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
{
	/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
	if (atomic_add_unless(atomic, -1, 1))
		return 0;

	/* Otherwise do it the slow way */
	spin_lock(lock);
	if (atomic_dec_and_test(atomic))
		return 1;
	spin_unlock(lock);
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds (pre-git)
24
45.28%
1
33.33%
David S. Miller
23
43.40%
1
33.33%
Nicholas Piggin
6
11.32%
1
33.33%
Total
53
100.00%
3
100.00%


EXPORT_SYMBOL(_atomic_dec_and_lock);
Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Linus Torvalds (pre-git)
29
42.65%
1
14.29%
David S. Miller
23
33.82%
1
14.29%
Nicholas Piggin
7
10.29%
1
14.29%
Linus Torvalds
7
10.29%
2
28.57%
Arun Sharma
1
1.47%
1
14.29%
Paul Gortmaker
1
1.47%
1
14.29%
Total
68
100.00%
7
100.00%
Directory: lib

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