A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-30 03:27:44 -04:00
Code Issues Projects Releases Packages Wiki Activity

Generic semaphore implementation

Browse source 
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 <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
This commit is contained in:
Matthew Wilcox 2008-03-07 21:55:58 -05:00 • committed by Matthew Wilcox
commit 64ac24e738
113 changed files with 314 additions and 7679 deletions
Download patch file Download diff file Expand all files Collapse all files

170
include/asm-mn10300/semaphore.h
View file

@ -1,169 +1 @@
/* MN10300 Semaphores
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#ifndef _ASM_SEMAPHORE_H
#define _ASM_SEMAPHORE_H
#ifndef __ASSEMBLY__
#include <linux/linkage.h>
#include <linux/wait.h>
#include <linux/spinlock.h>
#include <linux/rwsem.h>
#define SEMAPHORE_DEBUG 0
/*
* the semaphore definition
* - if count is >0 then there are tokens available on the semaphore for down
* to collect
* - if count is <=0 then there are no spare tokens, and anyone that wants one
* must wait
* - if wait_list is not empty, then there are processes waiting for the
* semaphore
*/
struct semaphore {
atomic_t count; /* it's not really atomic, it's
* just that certain modules
* expect to be able to access
* it directly */
spinlock_t wait_lock;
struct list_head wait_list;
#if SEMAPHORE_DEBUG
unsigned __magic;
#endif
};
#if SEMAPHORE_DEBUG
# define __SEM_DEBUG_INIT(name) , (long)&(name).__magic
#else
# define __SEM_DEBUG_INIT(name)
#endif
#define __SEMAPHORE_INITIALIZER(name, init_count) \
{ \
.count = ATOMIC_INIT(init_count), \
.wait_lock = __SPIN_LOCK_UNLOCKED((name).wait_lock), \
.wait_list = LIST_HEAD_INIT((name).wait_list) \
__SEM_DEBUG_INIT(name) \
}
#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
struct semaphore name = __SEMAPHORE_INITIALIZER(name, count)
#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0)
static inline void sema_init(struct semaphore *sem, int val)
{
*sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
}
static inline void init_MUTEX(struct semaphore *sem)
{
sema_init(sem, 1);
}
static inline void init_MUTEX_LOCKED(struct semaphore *sem)
{
sema_init(sem, 0);
}
extern void __down(struct semaphore *sem, unsigned long flags);
extern int __down_interruptible(struct semaphore *sem, unsigned long flags);
extern void __up(struct semaphore *sem);
static inline void down(struct semaphore *sem)
{
unsigned long flags;
int count;
#if SEMAPHORE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
spin_lock_irqsave(&sem->wait_lock, flags);
count = atomic_read(&sem->count);
if (likely(count > 0)) {
atomic_set(&sem->count, count - 1);
spin_unlock_irqrestore(&sem->wait_lock, flags);
} else {
__down(sem, flags);
}
}
static inline int down_interruptible(struct semaphore *sem)
{
unsigned long flags;
int count, ret = 0;
#if SEMAPHORE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
spin_lock_irqsave(&sem->wait_lock, flags);
count = atomic_read(&sem->count);
if (likely(count > 0)) {
atomic_set(&sem->count, count - 1);
spin_unlock_irqrestore(&sem->wait_lock, flags);
} else {
ret = __down_interruptible(sem, flags);
}
return ret;
}
/*
* non-blockingly attempt to down() a semaphore.
* - returns zero if we acquired it
*/
static inline int down_trylock(struct semaphore *sem)
{
unsigned long flags;
int count, success = 0;
#if SEMAPHORE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
spin_lock_irqsave(&sem->wait_lock, flags);
count = atomic_read(&sem->count);
if (likely(count > 0)) {
atomic_set(&sem->count, count - 1);
success = 1;
}
spin_unlock_irqrestore(&sem->wait_lock, flags);
return !success;
}
static inline void up(struct semaphore *sem)
{
unsigned long flags;
#if SEMAPHORE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
spin_lock_irqsave(&sem->wait_lock, flags);
if (!list_empty(&sem->wait_list))
__up(sem);
else
atomic_set(&sem->count, atomic_read(&sem->count) + 1);
spin_unlock_irqrestore(&sem->wait_lock, flags);
}
static inline int sem_getcount(struct semaphore *sem)
{
return atomic_read(&sem->count);
}
#endif /* __ASSEMBLY__ */
#endif
#include <linux/semaphore.h>