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spinlock.h revision 1.4 
      1 /*	$NetBSD: spinlock.h,v 1.4 2014/08/23 08:03:33 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2013 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Taylor R. Campbell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #ifndef _LINUX_SPINLOCK_H_
     33 #define _LINUX_SPINLOCK_H_
     34 
     35 #include <sys/cdefs.h>
     36 #include <sys/mutex.h>
     37 
     38 #define	__acquires(lock)	/* XXX lockdep stuff */
     39 #define	__releases(lock)	/* XXX lockdep stuff */
     40 
     41 typedef struct spinlock {
     42 	kmutex_t sl_lock;
     43 } spinlock_t;
     44 
     45 static inline int
     46 spin_is_locked(spinlock_t *spinlock)
     47 {
     48 	return mutex_owned(&spinlock->sl_lock);
     49 }
     50 
     51 static inline void
     52 spin_lock(spinlock_t *spinlock)
     53 {
     54 	mutex_enter(&spinlock->sl_lock);
     55 }
     56 
     57 static inline void
     58 spin_unlock(spinlock_t *spinlock)
     59 {
     60 	mutex_exit(&spinlock->sl_lock);
     61 }
     62 
     63 static inline void
     64 spin_lock_irq(spinlock_t *spinlock)
     65 {
     66 	spin_lock(spinlock);
     67 }
     68 
     69 static inline void
     70 spin_unlock_irq(spinlock_t *spinlock)
     71 {
     72 	spin_unlock(spinlock);
     73 }
     74 
     75 /* Must be a macro because the second argument is to be assigned.  */
     76 #define	spin_lock_irqsave(SPINLOCK, FLAGS)				\
     77 	do {								\
     78 		(FLAGS) = 0;						\
     79 		mutex_enter(&((spinlock_t *)(SPINLOCK))->sl_lock);	\
     80 	} while (0)
     81 
     82 static inline void
     83 spin_unlock_irqrestore(spinlock_t *spinlock, unsigned long __unused flags)
     84 {
     85 	mutex_exit(&spinlock->sl_lock);
     86 }
     87 
     88 static inline void
     89 spin_lock_init(spinlock_t *spinlock)
     90 {
     91 	/* XXX What's the right IPL?  IPL_DRM...?  */
     92 	mutex_init(&spinlock->sl_lock, MUTEX_DEFAULT, IPL_VM);
     93 }
     94 
     95 /*
     96  * XXX Linux doesn't ever destroy spin locks, it seems.  We'll have to
     97  * kludge it up.
     98  */
     99 
    100 static inline void
    101 spin_lock_destroy(spinlock_t *spinlock)
    102 {
    103 	mutex_destroy(&spinlock->sl_lock);
    104 }
    105 
    106 /* This is a macro to make the panic message clearer.  */
    107 #define	assert_spin_locked(spinlock)	\
    108 	KASSERT(mutex_owned(&(spinlock)->sl_lock))
    109 
    110 /*
    111  * Linux rwlocks are reader/writer spin locks.  We implement them as
    112  * normal spin locks without reader/writer semantics for expedience.
    113  * If that turns out to not work, adapting to reader/writer semantics
    114  * shouldn't be too hard.
    115  */
    116 
    117 #define	rwlock_t		spinlock_t
    118 #define	rwlock_init		spin_lock_init
    119 #define	rwlock_destroy		spin_lock_destroy
    120 #define	write_lock_irq		spin_lock_irq
    121 #define	write_unlock_irq	spin_unlock_irq
    122 #define	read_lock		spin_lock
    123 #define	read_unlock		spin_unlock
    124 
    125 #endif  /* _LINUX_SPINLOCK_H_ */
    126