[PATCH] s390: spin lock retry
[linux-2.6.git] / arch / s390 / lib / spinlock.c
1 /*
2  *  arch/s390/lib/spinlock.c
3  *    Out of line spinlock code.
4  *
5  *  S390 version
6  *    Copyright (C) 2004 IBM Deutschland Entwicklung GmbH, IBM Corporation
7  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
8  */
9
10 #include <linux/types.h>
11 #include <linux/module.h>
12 #include <linux/spinlock.h>
13 #include <linux/init.h>
14 #include <asm/io.h>
15
16 atomic_t spin_retry_counter;
17 int spin_retry = 1000;
18
19 /**
20  * spin_retry= parameter
21  */
22 static int __init spin_retry_setup(char *str)
23 {
24         spin_retry = simple_strtoul(str, &str, 0);
25         return 1;
26 }
27 __setup("spin_retry=", spin_retry_setup);
28
29 static inline void
30 _diag44(void)
31 {
32 #ifdef __s390x__
33         if (MACHINE_HAS_DIAG44)
34 #endif
35                 asm volatile("diag 0,0,0x44");
36 }
37
38 void
39 _raw_spin_lock_wait(spinlock_t *lp, unsigned int pc)
40 {
41         int count = spin_retry;
42
43         while (1) {
44                 if (count-- <= 0) {
45                         _diag44();
46                         count = spin_retry;
47                 }
48                 atomic_inc(&spin_retry_counter);
49                 if (_raw_compare_and_swap(&lp->lock, 0, pc) == 0)
50                         return;
51         }
52 }
53 EXPORT_SYMBOL(_raw_spin_lock_wait);
54
55 int
56 _raw_spin_trylock_retry(spinlock_t *lp, unsigned int pc)
57 {
58         int count = spin_retry;
59
60         while (count-- > 0) {
61                 atomic_inc(&spin_retry_counter);
62                 if (_raw_compare_and_swap(&lp->lock, 0, pc) == 0)
63                         return 1;
64         }
65         return 0;
66 }
67 EXPORT_SYMBOL(_raw_spin_trylock_retry);
68
69 void
70 _raw_read_lock_wait(rwlock_t *rw)
71 {
72         unsigned int old;
73         int count = spin_retry;
74
75         while (1) {
76                 if (count-- <= 0) {
77                         _diag44();
78                         count = spin_retry;
79                 }
80                 atomic_inc(&spin_retry_counter);
81                 old = rw->lock & 0x7fffffffU;
82                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
83                         return;
84         }
85 }
86 EXPORT_SYMBOL(_raw_read_lock_wait);
87
88 int
89 _raw_read_trylock_retry(rwlock_t *rw)
90 {
91         unsigned int old;
92         int count = spin_retry;
93
94         while (count-- > 0) {
95                 atomic_inc(&spin_retry_counter);
96                 old = rw->lock & 0x7fffffffU;
97                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
98                         return 1;
99         }
100         return 0;
101 }
102 EXPORT_SYMBOL(_raw_read_trylock_retry);
103
104 void
105 _raw_write_lock_wait(rwlock_t *rw)
106 {
107         int count = spin_retry;
108
109         while (1) {
110                 if (count-- <= 0) {
111                         _diag44();
112                         count = spin_retry;
113                 }
114                 atomic_inc(&spin_retry_counter);
115                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
116                         return;
117         }
118 }
119 EXPORT_SYMBOL(_raw_write_lock_wait);
120
121 int
122 _raw_write_trylock_retry(rwlock_t *rw)
123 {
124         int count = spin_retry;
125
126         while (count-- > 0) {
127                 atomic_inc(&spin_retry_counter);
128                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
129                         return 1;
130         }
131         return 0;
132 }
133 EXPORT_SYMBOL(_raw_write_trylock_retry);