fs/xfs/linux-2.6/sema.h

   1 /*
   2  * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #ifndef __XFS_SUPPORT_SEMA_H__
  19 #define __XFS_SUPPORT_SEMA_H__
  20
  21 #include <linux/time.h>
  22 #include <linux/wait.h>
  23 #include <linux/semaphore.h>
  24 #include <asm/atomic.h>
  25
  26 /*
  27  * sema_t structure just maps to struct semaphore in Linux kernel.
  28  */
  29
  30 typedef struct semaphore sema_t;
  31
  32 #define initnsema(sp, val, name)        sema_init(sp, val)
  33 #define psema(sp, b)                    down(sp)
  34 #define vsema(sp)                       up(sp)
  35 #define freesema(sema)                  do { } while (0)
  36
  37 static inline int issemalocked(sema_t *sp)
  38 {
  39         return down_trylock(sp) || (up(sp), 0);
  40 }
  41
  42 /*
  43  * Map cpsema (try to get the sema) to down_trylock. We need to switch
  44  * the return values since cpsema returns 1 (acquired) 0 (failed) and
  45  * down_trylock returns the reverse 0 (acquired) 1 (failed).
  46  */
  47 static inline int cpsema(sema_t *sp)
  48 {
  49         return down_trylock(sp) ? 0 : 1;
  50 }
  51
  52 #endif /* __XFS_SUPPORT_SEMA_H__ */