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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-m68knommu
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-m68knommu')
-rw-r--r--include/asm-m68knommu/semaphore-helper.h82
-rw-r--r--include/asm-m68knommu/semaphore.h154
2 files changed, 1 insertions, 235 deletions
diff --git a/include/asm-m68knommu/semaphore-helper.h b/include/asm-m68knommu/semaphore-helper.h
deleted file mode 100644
index 43da7bc483c7..000000000000
--- a/include/asm-m68knommu/semaphore-helper.h
+++ /dev/null
@@ -1,82 +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
13/*
14 * These two _must_ execute atomically wrt each other.
15 */
16static inline void wake_one_more(struct semaphore * sem)
17{
18 atomic_inc(&sem->waking);
19}
20
21static inline int waking_non_zero(struct semaphore *sem)
22{
23 int ret;
24 unsigned long flags;
25
26 spin_lock_irqsave(&semaphore_wake_lock, flags);
27 ret = 0;
28 if (atomic_read(&sem->waking) > 0) {
29 atomic_dec(&sem->waking);
30 ret = 1;
31 }
32 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
33 return ret;
34}
35
36/*
37 * waking_non_zero_interruptible:
38 * 1 got the lock
39 * 0 go to sleep
40 * -EINTR interrupted
41 */
42static inline int waking_non_zero_interruptible(struct semaphore *sem,
43 struct task_struct *tsk)
44{
45 int ret;
46 unsigned long flags;
47
48 spin_lock_irqsave(&semaphore_wake_lock, flags);
49 ret = 0;
50 if (atomic_read(&sem->waking) > 0) {
51 atomic_dec(&sem->waking);
52 ret = 1;
53 } else if (signal_pending(tsk)) {
54 atomic_inc(&sem->count);
55 ret = -EINTR;
56 }
57 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
58 return ret;
59}
60
61/*
62 * waking_non_zero_trylock:
63 * 1 failed to lock
64 * 0 got the lock
65 */
66static inline int waking_non_zero_trylock(struct semaphore *sem)
67{
68 int ret;
69 unsigned long flags;
70
71 spin_lock_irqsave(&semaphore_wake_lock, flags);
72 ret = 1;
73 if (atomic_read(&sem->waking) > 0) {
74 atomic_dec(&sem->waking);
75 ret = 0;
76 } else
77 atomic_inc(&sem->count);
78 spin_unlock_irqrestore(&semaphore_wake_lock, flags);
79 return ret;
80}
81
82#endif
diff --git a/include/asm-m68knommu/semaphore.h b/include/asm-m68knommu/semaphore.h
index 5779eb6c0689..d9b2034ed1d2 100644
--- a/include/asm-m68knommu/semaphore.h
+++ b/include/asm-m68knommu/semaphore.h
@@ -1,153 +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
13#include <asm/system.h>
14#include <asm/atomic.h>
15
16/*
17 * Interrupt-safe semaphores..
18 *
19 * (C) Copyright 1996 Linus Torvalds
20 *
21 * m68k version by Andreas Schwab
22 */
23
24
25struct semaphore {
26 atomic_t count;
27 atomic_t waking;
28 wait_queue_head_t wait;
29};
30
31#define __SEMAPHORE_INITIALIZER(name, n) \
32{ \
33 .count = ATOMIC_INIT(n), \
34 .waking = ATOMIC_INIT(0), \
35 .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
36}
37
38#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
39 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
40
41#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
42
43static inline void sema_init (struct semaphore *sem, int val)
44{
45 *sem = (struct semaphore)__SEMAPHORE_INITIALIZER(*sem, val);
46}
47
48static inline void init_MUTEX (struct semaphore *sem)
49{
50 sema_init(sem, 1);
51}
52
53static inline void init_MUTEX_LOCKED (struct semaphore *sem)
54{
55 sema_init(sem, 0);
56}
57
58asmlinkage void __down_failed(void /* special register calling convention */);
59asmlinkage int __down_failed_interruptible(void /* params in registers */);
60asmlinkage int __down_failed_trylock(void /* params in registers */);
61asmlinkage void __up_wakeup(void /* special register calling convention */);
62
63asmlinkage void __down(struct semaphore * sem);
64asmlinkage int __down_interruptible(struct semaphore * sem);
65asmlinkage int __down_trylock(struct semaphore * sem);
66asmlinkage void __up(struct semaphore * sem);
67
68extern spinlock_t semaphore_wake_lock;
69
70/*
71 * This is ugly, but we want the default case to fall through.
72 * "down_failed" is a special asm handler that calls the C
73 * routine that actually waits. See arch/m68k/lib/semaphore.S
74 */
75static inline void down(struct semaphore * sem)
76{
77 might_sleep();
78 __asm__ __volatile__(
79 "| atomic down operation\n\t"
80 "movel %0, %%a1\n\t"
81 "lea %%pc@(1f), %%a0\n\t"
82 "subql #1, %%a1@\n\t"
83 "jmi __down_failed\n"
84 "1:"
85 : /* no outputs */
86 : "g" (sem)
87 : "cc", "%a0", "%a1", "memory");
88}
89
90static inline int down_interruptible(struct semaphore * sem)
91{
92 int ret;
93
94 might_sleep();
95 __asm__ __volatile__(
96 "| atomic down operation\n\t"
97 "movel %1, %%a1\n\t"
98 "lea %%pc@(1f), %%a0\n\t"
99 "subql #1, %%a1@\n\t"
100 "jmi __down_failed_interruptible\n\t"
101 "clrl %%d0\n"
102 "1: movel %%d0, %0\n"
103 : "=d" (ret)
104 : "g" (sem)
105 : "cc", "%d0", "%a0", "%a1", "memory");
106 return(ret);
107}
108
109static inline int down_trylock(struct semaphore * sem)
110{
111 register struct semaphore *sem1 __asm__ ("%a1") = sem;
112 register int result __asm__ ("%d0");
113
114 __asm__ __volatile__(
115 "| atomic down trylock operation\n\t"
116 "subql #1,%1@\n\t"
117 "jmi 2f\n\t"
118 "clrl %0\n"
119 "1:\n"
120 ".section .text.lock,\"ax\"\n"
121 ".even\n"
122 "2:\tpea 1b\n\t"
123 "jbra __down_failed_trylock\n"
124 ".previous"
125 : "=d" (result)
126 : "a" (sem1)
127 : "memory");
128 return result;
129}
130
131/*
132 * Note! This is subtle. We jump to wake people up only if
133 * the semaphore was negative (== somebody was waiting on it).
134 * The default case (no contention) will result in NO
135 * jumps for both down() and up().
136 */
137static inline void up(struct semaphore * sem)
138{
139 __asm__ __volatile__(
140 "| atomic up operation\n\t"
141 "movel %0, %%a1\n\t"
142 "lea %%pc@(1f), %%a0\n\t"
143 "addql #1, %%a1@\n\t"
144 "jle __up_wakeup\n"
145 "1:"
146 : /* no outputs */
147 : "g" (sem)
148 : "cc", "%a0", "%a1", "memory");
149}
150
151#endif /* __ASSEMBLY__ */
152
153#endif
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