1 /*
2 * arch/alpha/lib/dec_and_lock.c
3 *
4 * ll/sc version of atomic_dec_and_lock()
5 *
6 */
7
8 #include <linux/spinlock.h>
9 #include <linux/atomic.h>
10 #include <linux/export.h>
11
12 asm (".text \n\
13 .global _atomic_dec_and_lock \n\
14 .ent _atomic_dec_and_lock \n\
15 .align 4 \n\
16 _atomic_dec_and_lock: \n\
17 .prologue 0 \n\
18 1: ldl_l $1, 0($16) \n\
19 subl $1, 1, $1 \n\
20 beq $1, 2f \n\
21 stl_c $1, 0($16) \n\
22 beq $1, 4f \n\
23 mb \n\
24 clr $0 \n\
25 ret \n\
26 2: br $29, 3f \n\
27 3: ldgp $29, 0($29) \n\
28 br $atomic_dec_and_lock_1..ng \n\
29 .subsection 2 \n\
30 4: br 1b \n\
31 .previous \n\
32 .end _atomic_dec_and_lock");
33
atomic_dec_and_lock_1(atomic_t * atomic,spinlock_t * lock)34 static int __used atomic_dec_and_lock_1(atomic_t *atomic, spinlock_t *lock)
35 {
36 /* Slow path */
37 spin_lock(lock);
38 if (atomic_dec_and_test(atomic))
39 return 1;
40 spin_unlock(lock);
41 return 0;
42 }
43 EXPORT_SYMBOL(_atomic_dec_and_lock);
44