1 /* 2 * Copyright (c) 2015 Michael Neumann <mneumann@ntecs.de> 3 * All rights reserved. 4 * Copyright (c) 2003-2011 The DragonFly Project. All rights reserved. 5 * 6 * This code is derived from software contributed to The DragonFly Project 7 * by Michael Neumann <mneumann@ntecs.de> and 8 * Matthew Dillon <dillon@backplane.com> 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 unmodified, this list of conditions, and the following 15 * disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #ifndef _LINUX_WW_MUTEX_H_ 33 #define _LINUX_WW_MUTEX_H_ 34 35 #include <linux/mutex.h> 36 37 /* 38 * A basic, unoptimized implementation of wound/wait mutexes for DragonFly 39 * modelled after the Linux API [1]. 40 * 41 * [1]: http://lxr.free-electrons.com/source/include/linux/ww_mutex.h 42 */ 43 44 #include <sys/errno.h> 45 #include <sys/types.h> 46 #include <machine/atomic.h> 47 48 struct ww_class { 49 volatile u_long stamp; 50 const char *name; 51 }; 52 53 struct ww_acquire_ctx { 54 u_long stamp; 55 int acquired; 56 int unused01; 57 struct ww_class *ww_class; 58 }; 59 60 struct ww_mutex { 61 struct lock base; 62 struct ww_acquire_ctx *ctx; 63 u_long stamp; /* heuristic */ 64 int blocked; 65 int unused01; 66 }; 67 68 #define DEFINE_WW_CLASS(classname) \ 69 struct ww_class classname = { \ 70 .stamp = 0, \ 71 .name = #classname \ 72 } 73 74 extern void ww_acquire_init(struct ww_acquire_ctx *ctx, 75 struct ww_class *ww_class); 76 extern void ww_acquire_done(struct ww_acquire_ctx *ctx); 77 extern void ww_acquire_fini(struct ww_acquire_ctx *ctx); 78 extern void ww_mutex_init(struct ww_mutex *ww, struct ww_class *ww_class); 79 extern int ww_mutex_lock(struct ww_mutex *ww, struct ww_acquire_ctx *ctx); 80 extern int ww_mutex_lock_slow(struct ww_mutex *ww, struct ww_acquire_ctx *ctx); 81 extern int ww_mutex_lock_interruptible(struct ww_mutex *ww, 82 struct ww_acquire_ctx *ctx); 83 extern int ww_mutex_lock_slow_interruptible(struct ww_mutex *ww, 84 struct ww_acquire_ctx *ctx); 85 extern void ww_mutex_unlock(struct ww_mutex *ww); 86 extern void ww_mutex_destroy(struct ww_mutex *ww); 87 88 /* 89 * Returns 1 if locked, 0 otherwise 90 */ 91 static inline bool 92 ww_mutex_is_locked(struct ww_mutex *ww) 93 { 94 return (lockstatus(&ww->base, NULL) != 0); 95 } 96 97 /* 98 * Returns 1 on success, 0 if contended. 99 * 100 * This call has no context accounting. 101 */ 102 static inline int 103 ww_mutex_trylock(struct ww_mutex *ww) 104 { 105 return (lockmgr(&ww->base, LK_EXCLUSIVE|LK_NOWAIT) == 0); 106 } 107 108 #endif /* _LINUX_WW_MUTEX_H_ */ 109