root/kern/include/wchan.h

INCLUDED FROM

   1 /*
   2  * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
   3  *      The President and Fellows of Harvard College.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  30 #ifndef _WCHAN_H_
  31 #define _WCHAN_H_
  33 /*
  34  * Wait channel.
  35  */
  38 struct wchan; /* Opaque */
  40 /*
  41  * Create a wait channel. Use NAME as a symbolic name for the channel.
  42  * NAME should be a string constant; if not, the caller is responsible
  43  * for freeing it after the wchan is destroyed.
  44  */
  45 struct wchan *wchan_create(const char *name);
  47 /*
  48  * Destroy a wait channel. Must be empty and unlocked.
  49  */
  50 void wchan_destroy(struct wchan *wc);
  52 /*
  53  * Return nonzero if there are no threads sleeping on the channel.
  54  * This is meant to be used only for diagnostic purposes.
  55  */
bool wchan_isempty(struct wchan *wc);
  58 /*
  59  * Lock and unlock the wait channel.
  60  */
  61 void wchan_lock(struct wchan *wc);
  62 void wchan_unlock(struct wchan *wc);
  64 /*
  65  * Go to sleep on a wait channel. The current thread is suspended
  66  * until awakened by someone else, at which point this function
  67  * returns.
  68  *
  69  * The channel must be locked, and will have been *unlocked* upon
  70  * return.
  71  */
  72 void wchan_sleep(struct wchan *wc);
  74 /*
  75  * Wake up one thread, or all threads, sleeping on a wait channel.
  76  * The queue should not already be locked.
  77  *
  78  * The current implementation is FIFO but this is not promised by the
  79  * interface.
  80  */
  81 void wchan_wakeone(struct wchan *wc);
  82 void wchan_wakeall(struct wchan *wc);
  85 #endif /* _WCHAN_H_ */