root/kern/include/spinlock.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 _SPINLOCK_H_
  31 #define _SPINLOCK_H_
  33 /*
  34  * Spinlocks. While the guts are machine-dependent, the structure and the
  35  * basic functions are supposed to be the same across all machines.
  36  */
  38 #include <cdefs.h>
  40 /* Inlining support - for making sure an out-of-line copy gets built */
  41 #ifndef SPINLOCK_INLINE
  42 #define SPINLOCK_INLINE INLINE
  43 #endif
  45 /* Get the machine-dependent bits. */
  46 #include <machine/spinlock.h>
  48 /*
  49  * Basic spinlock.
  50  *
  51  * Note that spinlocks are held by CPUs, not by threads.
  52  *
  53  * This structure is made public so spinlocks do not have to be
  54  * malloc'd; however, code that uses spinlocks should not look inside
  55  * the structure directly but always use the spinlock API functions.
  56  */
  57 struct spinlock {
  58         volatile spinlock_data_t lk_lock; /* The memory word where we spin. */
  59         struct cpu *lk_holder;          /* CPU holding this lock. */
  60 };
  62 /*
  63  * Initializer for cases where a spinlock needs to be static or global.
  64  */
  65 #define SPINLOCK_INITIALIZER    { SPINLOCK_DATA_INITIALIZER, NULL }
  67 /*
  68  * Spinlock functions.
  69  *
  70  * init         Initialize the contents of a spinlock.
  71  * cleanup      Opposite of init. Lock must be unlocked.
  72  *
  73  * acquire      Get the lock, spinning as necessary. Also disables interrupts.
  74  * release      Release the lock. May re-enable interrupts.
  75  *
  76  * do_i_hold    Check if the current CPU holds the lock.
  77  */
  79 void spinlock_init(struct spinlock *lk);
  80 void spinlock_cleanup(struct spinlock *lk);
  82 void spinlock_acquire(struct spinlock *lk);
  83 void spinlock_release(struct spinlock *lk);
bool spinlock_do_i_hold(struct spinlock *lk);
  88 #endif /* _SPINLOCK_H_ */