sx.h revision 73782
1/* 2 * Copyright (C) 2001 Jason Evans <jasone@freebsd.org>. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice(s), this list of conditions and the following disclaimer as 9 * the first lines of this file unmodified other than the possible 10 * addition of one or more copyright notices. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice(s), 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 COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 16 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 20 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 25 * DAMAGE. 26 * 27 * $FreeBSD: head/sys/sys/sx.h 73782 2001-03-05 19:59:41Z jasone $ 28 */ 29 30#ifndef _SYS_SX_H_ 31#define _SYS_SX_H_ 32 33#ifndef LOCORE 34#include <sys/mutex.h> 35#include <sys/condvar.h> 36 37struct sx { 38 struct mtx sx_lock; /* General protection lock and xlock. */ 39 int sx_cnt; /* -1: xlock, > 0: slock count. */ 40 struct cv sx_shrd_cv; /* slock waiters. */ 41 int sx_shrd_wcnt; /* Number of slock waiters. */ 42 struct cv sx_excl_cv; /* xlock waiters. */ 43 int sx_excl_wcnt; /* Number of xlock waiters. */ 44}; 45 46#ifdef _KERNEL 47void sx_init(struct sx *sx, const char *description); 48void sx_destroy(struct sx *sx); 49void sx_slock(struct sx *sx); 50void sx_xlock(struct sx *sx); 51void sx_sunlock(struct sx *sx); 52void sx_xunlock(struct sx *sx); 53 54#ifdef INVARIANTS 55/* 56 * SX_ASSERT_SLOCKED() can only detect that at least *some* thread owns an 57 * slock, but it cannot guarantee that *this* thread owns an slock. 58 */ 59#define SX_ASSERT_SLOCKED(sx) do { \ 60 mtx_lock(&(sx)->sx_lock); \ 61 KASSERT(((sx)->sx_cnt > 0), ("%s: lacking slock\n", \ 62 __FUNCTION__)); \ 63 mtx_unlock(&(sx)->sx_lock); \ 64} while (0) 65/* 66 * SX_ASSERT_XLOCKED() can only detect that at least *some* thread owns an 67 * xlock, but it cannot guarantee that *this* thread owns an xlock. 68 */ 69#define SX_ASSERT_XLOCKED(sx) do { \ 70 mtx_lock(&(sx)->sx_lock); \ 71 KASSERT(((sx)->sx_cnt == -1), ("%s: lacking xlock\n", \ 72 __FUNCTION__)); \ 73 mtx_unlock(&(sx)->sx_lock); \ 74} while (0) 75#else /* INVARIANTS */ 76#define SX_ASSERT_SLOCKED(sx) 77#define SX_ASSERT_XLOCKER(sx) 78#endif /* INVARIANTS */ 79 80#endif /* _KERNEL */ 81#endif /* !LOCORE */ 82#endif /* _SYS_SX_H_ */ 83