The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/umtx.h

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    1 /*-
    2  * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
    3  * All rights reserved.
    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 unmodified, this list of conditions, and the following
   10  *    disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   25  *
   26  * $FreeBSD$
   27  *
   28  */
   29 
   30 #ifndef _SYS_UMTX_H_
   31 #define _SYS_UMTX_H_
   32 
   33 #include <sys/limits.h>
   34 
   35 /* 
   36  * See pthread_*
   37  */
   38 
   39 #define UMTX_UNOWNED    0x0
   40 #define UMTX_CONTESTED  LONG_MIN
   41 
   42 struct umtx {
   43         void    *u_owner;       /* Owner of the mutex. */
   44 };
   45 
   46 /* op code for _umtx_op */
   47 #define UMTX_OP_LOCK            0
   48 #define UMTX_OP_UNLOCK          1
   49 #define UMTX_OP_WAIT            2
   50 #define UMTX_OP_WAKE            3
   51 
   52 #ifndef _KERNEL
   53 
   54 /*
   55  * System calls for acquiring and releasing contested mutexes.
   56  */
   57 /* deprecated becaues it can only use thread id */
   58 int _umtx_lock(struct umtx *mtx);
   59 /* deprecated becaues it can only use thread id */
   60 int _umtx_unlock(struct umtx *mtx);
   61 int _umtx_op(struct umtx *umtx, int op, long id, void *uaddr, void *uaddr2);
   62 
   63 /*
   64  * Standard api.  Try uncontested acquire/release and asks the
   65  * kernel to resolve failures.
   66  */
   67 static __inline void
   68 umtx_init(struct umtx *umtx)
   69 {
   70         umtx->u_owner = UMTX_UNOWNED;
   71 }
   72 
   73 static __inline long
   74 umtx_owner(struct umtx *umtx)
   75 {
   76         return ((long)umtx->u_owner & ~LONG_MIN);
   77 }
   78 
   79 static __inline int
   80 umtx_lock(struct umtx *umtx, long id)
   81 {
   82         if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
   83             (void *)id) == 0)
   84                 if (_umtx_lock(umtx) == -1)
   85                         return (errno);
   86         return (0);
   87 }
   88 
   89 static __inline int
   90 umtx_trylock(struct umtx *umtx, long id)
   91 {
   92         if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
   93             (void *)id) == 0)
   94                 return (EBUSY);
   95         return (0);
   96 }
   97 
   98 static __inline int
   99 umtx_timedlock(struct umtx *umtx, long id, const struct timespec *timeout)
  100 {
  101         if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
  102             (void *)id) == 0)
  103                 if (_umtx_op(umtx, UMTX_OP_LOCK, id, 0, (void *)timeout) == -1)
  104                         return (errno);
  105         return (0);
  106 }
  107 
  108 static __inline int
  109 umtx_unlock(struct umtx *umtx, long id)
  110 {
  111         if (atomic_cmpset_rel_ptr(&umtx->u_owner, (void *)id,
  112             (void *)UMTX_UNOWNED) == 0)
  113                 if (_umtx_unlock(umtx) == -1)
  114                         return (errno);
  115         return (0);
  116 }
  117 
  118 static __inline int
  119 umtx_wait(struct umtx *umtx, long id, const struct timespec *timeout)
  120 {
  121         if (_umtx_op(umtx, UMTX_OP_WAIT, id, 0, (void *)timeout) == -1)
  122                 return (errno);
  123         return (0);
  124 }
  125 
  126 /* Wake threads waiting on a user address. */
  127 static __inline int
  128 umtx_wake(struct umtx *umtx, int nr_wakeup)
  129 {
  130         if (_umtx_op(umtx, UMTX_OP_WAKE, nr_wakeup, 0, 0) == -1)
  131                 return (errno);
  132         return (0);
  133 }
  134 #else
  135 
  136 struct umtx_q *umtxq_alloc(void);
  137 void umtxq_free(struct umtx_q *);
  138 struct thread;
  139 int kern_umtx_wake(struct thread *td, void *uaddr, int n_wake);
  140 
  141 #endif /* !_KERNEL */
  142 #endif /* !_SYS_UMTX_H_ */

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