Linux-2.6.12-rc2
[linux-3.10.git] / arch / alpha / lib / dec_and_lock.c
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 <asm/atomic.h>
10
11   asm (".text                                   \n\
12         .global _atomic_dec_and_lock            \n\
13         .ent _atomic_dec_and_lock               \n\
14         .align  4                               \n\
15 _atomic_dec_and_lock:                           \n\
16         .prologue 0                             \n\
17 1:      ldl_l   $1, 0($16)                      \n\
18         subl    $1, 1, $1                       \n\
19         beq     $1, 2f                          \n\
20         stl_c   $1, 0($16)                      \n\
21         beq     $1, 4f                          \n\
22         mb                                      \n\
23         clr     $0                              \n\
24         ret                                     \n\
25 2:      br      $29, 3f                         \n\
26 3:      ldgp    $29, 0($29)                     \n\
27         br      $atomic_dec_and_lock_1..ng      \n\
28         .subsection 2                           \n\
29 4:      br      1b                              \n\
30         .previous                               \n\
31         .end _atomic_dec_and_lock");
32
33 static int __attribute_used__
34 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 }