1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * arch/alpha/lib/dec_and_lock.c
4 *
5 * ll/sc version of atomic_dec_and_lock()
6 *
7 */
8
9 #include <linux/spinlock.h>
10 #include <linux/atomic.h>
11 #include <linux/export.h>
12
13 asm (".text \n\
14 .global _atomic_dec_and_lock \n\
15 .ent _atomic_dec_and_lock \n\
16 .align 4 \n\
17 _atomic_dec_and_lock: \n\
18 .prologue 0 \n\
19 1: ldl_l $1, 0($16) \n\
20 subl $1, 1, $1 \n\
21 beq $1, 2f \n\
22 stl_c $1, 0($16) \n\
23 beq $1, 4f \n\
24 mb \n\
25 clr $0 \n\
26 ret \n\
27 2: br $29, 3f \n\
28 3: ldgp $29, 0($29) \n\
29 br $atomic_dec_and_lock_1..ng \n\
30 .subsection 2 \n\
31 4: br 1b \n\
32 .previous \n\
33 .end _atomic_dec_and_lock");
34
atomic_dec_and_lock_1(atomic_t * atomic,spinlock_t * lock)35 static int __used atomic_dec_and_lock_1(atomic_t *atomic, spinlock_t *lock)
36 {
37 /* Slow path */
38 spin_lock(lock);
39 if (atomic_dec_and_test(atomic))
40 return 1;
41 spin_unlock(lock);
42 return 0;
43 }
44 EXPORT_SYMBOL(_atomic_dec_and_lock);
45