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authorMatthew Wilcox <matthew@wil.cx>2008-03-07 21:55:58 -0500
committerMatthew Wilcox <willy@linux.intel.com>2008-04-17 10:42:34 -0400
commit64ac24e738823161693bf791f87adc802cf529ff (patch)
tree19c0b0cf314d4394ca580c05b86cdf874ce0a167 /include/asm-m68k
parente48b3deee475134585eed03e7afebe4bf9e0dba9 (diff)
Generic semaphore implementation
Semaphores are no longer performance-critical, so a generic C implementation is better for maintainability, debuggability and extensibility. Thanks to Peter Zijlstra for fixing the lockdep warning. Thanks to Harvey Harrison for pointing out that the unlikely() was unnecessary. Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Acked-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/asm-m68k')
-rw-r--r--include/asm-m68k/semaphore-helper.h142
-rw-r--r--include/asm-m68k/semaphore.h164
2 files changed, 1 insertions, 305 deletions
diff --git a/include/asm-m68k/semaphore-helper.h b/include/asm-m68k/semaphore-helper.h
deleted file mode 100644
index eef30ba0b499..000000000000
--- a/include/asm-m68k/semaphore-helper.h
+++ /dev/null
@@ -1,142 +0,0 @@
1#ifndef _M68K_SEMAPHORE_HELPER_H
2#define _M68K_SEMAPHORE_HELPER_H
3
4/*
5 * SMP- and interrupt-safe semaphores helper functions.
6 *
7 * (C) Copyright 1996 Linus Torvalds
8 *
9 * m68k version by Andreas Schwab
10 */
11
12#include <linux/errno.h>
13
14/*
15 * These two _must_ execute atomically wrt each other.
16 */
17static inline void wake_one_more(struct semaphore * sem)
18{
19 atomic_inc(&sem->waking);
20}
21
22#ifndef CONFIG_RMW_INSNS
23extern spinlock_t semaphore_wake_lock;
24#endif
25
26static inline int waking_non_zero(struct semaphore *sem)
27{
28 int ret;
29#ifndef CONFIG_RMW_INSNS
30 unsigned long flags;
31
32 spin_lock_irqsave(&semaphore_wake_lock, flags);
33 ret = 0;
34 if (atomic_read(&sem->waking) > 0) {
35 atomic_dec(&sem->waking);
36 ret = 1;
37 }
38 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
39#else
40 int tmp1, tmp2;
41
42 __asm__ __volatile__
43 ("1: movel %1,%2\n"
44 " jle 2f\n"
45 " subql #1,%2\n"
46 " casl %1,%2,%3\n"
47 " jne 1b\n"
48 " moveq #1,%0\n"
49 "2:"
50 : "=d" (ret), "=d" (tmp1), "=d" (tmp2)
51 : "m" (sem->waking), "0" (0), "1" (sem->waking));
52#endif
53
54 return ret;
55}
56
57/*
58 * waking_non_zero_interruptible:
59 * 1 got the lock
60 * 0 go to sleep
61 * -EINTR interrupted
62 */
63static inline int waking_non_zero_interruptible(struct semaphore *sem,
64 struct task_struct *tsk)
65{
66 int ret;
67#ifndef CONFIG_RMW_INSNS
68 unsigned long flags;
69
70 spin_lock_irqsave(&semaphore_wake_lock, flags);
71 ret = 0;
72 if (atomic_read(&sem->waking) > 0) {
73 atomic_dec(&sem->waking);
74 ret = 1;
75 } else if (signal_pending(tsk)) {
76 atomic_inc(&sem->count);
77 ret = -EINTR;
78 }
79 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
80#else
81 int tmp1, tmp2;
82
83 __asm__ __volatile__
84 ("1: movel %1,%2\n"
85 " jle 2f\n"
86 " subql #1,%2\n"
87 " casl %1,%2,%3\n"
88 " jne 1b\n"
89 " moveq #1,%0\n"
90 " jra %a4\n"
91 "2:"
92 : "=d" (ret), "=d" (tmp1), "=d" (tmp2)
93 : "m" (sem->waking), "i" (&&next), "0" (0), "1" (sem->waking));
94 if (signal_pending(tsk)) {
95 atomic_inc(&sem->count);
96 ret = -EINTR;
97 }
98next:
99#endif
100
101 return ret;
102}
103
104/*
105 * waking_non_zero_trylock:
106 * 1 failed to lock
107 * 0 got the lock
108 */
109static inline int waking_non_zero_trylock(struct semaphore *sem)
110{
111 int ret;
112#ifndef CONFIG_RMW_INSNS
113 unsigned long flags;
114
115 spin_lock_irqsave(&semaphore_wake_lock, flags);
116 ret = 1;
117 if (atomic_read(&sem->waking) > 0) {
118 atomic_dec(&sem->waking);
119 ret = 0;
120 } else
121 atomic_inc(&sem->count);
122 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
123#else
124 int tmp1, tmp2;
125
126 __asm__ __volatile__
127 ("1: movel %1,%2\n"
128 " jle 2f\n"
129 " subql #1,%2\n"
130 " casl %1,%2,%3\n"
131 " jne 1b\n"
132 " moveq #0,%0\n"
133 "2:"
134 : "=d" (ret), "=d" (tmp1), "=d" (tmp2)
135 : "m" (sem->waking), "0" (1), "1" (sem->waking));
136 if (ret)
137 atomic_inc(&sem->count);
138#endif
139 return ret;
140}
141
142#endif
diff --git a/include/asm-m68k/semaphore.h b/include/asm-m68k/semaphore.h
index 64d6b119bb0a..d9b2034ed1d2 100644
--- a/include/asm-m68k/semaphore.h
+++ b/include/asm-m68k/semaphore.h
@@ -1,163 +1 @@
1#ifndef _M68K_SEMAPHORE_H #include <linux/semaphore.h>
2#define _M68K_SEMAPHORE_H
3
4#define RW_LOCK_BIAS 0x01000000
5
6#ifndef __ASSEMBLY__
7
8#include <linux/linkage.h>
9#include <linux/wait.h>
10#include <linux/spinlock.h>
11#include <linux/rwsem.h>
12#include <linux/stringify.h>
13
14#include <asm/system.h>
15#include <asm/atomic.h>
16
17/*
18 * Interrupt-safe semaphores..
19 *
20 * (C) Copyright 1996 Linus Torvalds
21 *
22 * m68k version by Andreas Schwab
23 */
24
25
26struct semaphore {
27 atomic_t count;
28 atomic_t waking;
29 wait_queue_head_t wait;
30};
31
32#define __SEMAPHORE_INITIALIZER(name, n) \
33{ \
34 .count = ATOMIC_INIT(n), \
35 .waking = ATOMIC_INIT(0), \
36 .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
37}
38
39#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
40 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
41
42#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
43
44static inline void sema_init(struct semaphore *sem, int val)
45{
46 *sem = (struct semaphore)__SEMAPHORE_INITIALIZER(*sem, val);
47}
48
49static inline void init_MUTEX (struct semaphore *sem)
50{
51 sema_init(sem, 1);
52}
53
54static inline void init_MUTEX_LOCKED (struct semaphore *sem)
55{
56 sema_init(sem, 0);
57}
58
59asmlinkage void __down_failed(void /* special register calling convention */);
60asmlinkage int __down_failed_interruptible(void /* params in registers */);
61asmlinkage int __down_failed_trylock(void /* params in registers */);
62asmlinkage void __up_wakeup(void /* special register calling convention */);
63
64asmlinkage void __down(struct semaphore * sem);
65asmlinkage int __down_interruptible(struct semaphore * sem);
66asmlinkage int __down_trylock(struct semaphore * sem);
67asmlinkage void __up(struct semaphore * sem);
68
69/*
70 * This is ugly, but we want the default case to fall through.
71 * "down_failed" is a special asm handler that calls the C
72 * routine that actually waits. See arch/m68k/lib/semaphore.S
73 */
74static inline void down(struct semaphore *sem)
75{
76 register struct semaphore *sem1 __asm__ ("%a1") = sem;
77
78 might_sleep();
79 __asm__ __volatile__(
80 "| atomic down operation\n\t"
81 "subql #1,%0@\n\t"
82 "jmi 2f\n\t"
83 "1:\n"
84 LOCK_SECTION_START(".even\n\t")
85 "2:\tpea 1b\n\t"
86 "jbra __down_failed\n"
87 LOCK_SECTION_END
88 : /* no outputs */
89 : "a" (sem1)
90 : "memory");
91}
92
93static inline int down_interruptible(struct semaphore *sem)
94{
95 register struct semaphore *sem1 __asm__ ("%a1") = sem;
96 register int result __asm__ ("%d0");
97
98 might_sleep();
99 __asm__ __volatile__(
100 "| atomic interruptible down operation\n\t"
101 "subql #1,%1@\n\t"
102 "jmi 2f\n\t"
103 "clrl %0\n"
104 "1:\n"
105 LOCK_SECTION_START(".even\n\t")
106 "2:\tpea 1b\n\t"
107 "jbra __down_failed_interruptible\n"
108 LOCK_SECTION_END
109 : "=d" (result)
110 : "a" (sem1)
111 : "memory");
112 return result;
113}
114
115static inline int down_trylock(struct semaphore *sem)
116{
117 register struct semaphore *sem1 __asm__ ("%a1") = sem;
118 register int result __asm__ ("%d0");
119
120 __asm__ __volatile__(
121 "| atomic down trylock operation\n\t"
122 "subql #1,%1@\n\t"
123 "jmi 2f\n\t"
124 "clrl %0\n"
125 "1:\n"
126 LOCK_SECTION_START(".even\n\t")
127 "2:\tpea 1b\n\t"
128 "jbra __down_failed_trylock\n"
129 LOCK_SECTION_END
130 : "=d" (result)
131 : "a" (sem1)
132 : "memory");
133 return result;
134}
135
136/*
137 * Note! This is subtle. We jump to wake people up only if
138 * the semaphore was negative (== somebody was waiting on it).
139 * The default case (no contention) will result in NO
140 * jumps for both down() and up().
141 */
142static inline void up(struct semaphore *sem)
143{
144 register struct semaphore *sem1 __asm__ ("%a1") = sem;
145
146 __asm__ __volatile__(
147 "| atomic up operation\n\t"
148 "addql #1,%0@\n\t"
149 "jle 2f\n"
150 "1:\n"
151 LOCK_SECTION_START(".even\n\t")
152 "2:\t"
153 "pea 1b\n\t"
154 "jbra __up_wakeup\n"
155 LOCK_SECTION_END
156 : /* no outputs */
157 : "a" (sem1)
158 : "memory");
159}
160
161#endif /* __ASSEMBLY__ */
162
163#endif
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