sema.h

来自「linux 内核源代码」· C头文件 代码 · 共 53 行

/*
 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef __XFS_SUPPORT_SEMA_H__
#define __XFS_SUPPORT_SEMA_H__

#include <linux/time.h>
#include <linux/wait.h>
#include <asm/atomic.h>
#include <asm/semaphore.h>

/*
 * sema_t structure just maps to struct semaphore in Linux kernel.
 */

typedef struct semaphore sema_t;

#define initnsema(sp, val, name)	sema_init(sp, val)
#define psema(sp, b)			down(sp)
#define vsema(sp)			up(sp)
#define freesema(sema)			do { } while (0)

static inline int issemalocked(sema_t *sp)
{
	return down_trylock(sp) || (up(sp), 0);
}

/*
 * Map cpsema (try to get the sema) to down_trylock. We need to switch
 * the return values since cpsema returns 1 (acquired) 0 (failed) and
 * down_trylock returns the reverse 0 (acquired) 1 (failed).
 */
static inline int cpsema(sema_t *sp)
{
	return down_trylock(sp) ? 0 : 1;
}

#endif /* __XFS_SUPPORT_SEMA_H__ */