1 /* $NetBSD: psref.h,v 1.1 2016/04/09 06:21:16 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2016 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 _SYS_PSREF_H 33 #define _SYS_PSREF_H 34 35 #include <sys/types.h> 36 #include <sys/queue.h> 37 38 struct cpu_info; 39 struct lwp; 40 41 struct psref; 42 struct psref_class; 43 struct psref_target; 44 45 /* 46 * struct psref_target 47 * 48 * Bookkeeping for an object to which users can acquire passive 49 * references. This is compact so that it can easily be embedded 50 * into many multitudes of objects, e.g. IP packet flows. 51 * 52 * prt_draining is false on initialization, and may be written 53 * only once, to make it true, when someone has prevented new 54 * references from being created and wants to drain the target in 55 * order to destroy it. 56 */ 57 struct psref_target { 58 struct psref_class *prt_class; 59 bool prt_draining; 60 }; 61 62 /* 63 * struct psref 64 * 65 * Bookkeeping for a single passive reference. There should only 66 * be a few of these per CPU in the system at once, no matter how 67 * many targets are stored, so these are a bit larger than struct 68 * psref_target. The contents of struct psref may be read and 69 * written only on the local CPU. 70 */ 71 struct psref { 72 LIST_ENTRY(psref) psref_entry; 73 const struct psref_target *psref_target; 74 struct lwp *psref_lwp; 75 struct cpu_info *psref_cpu; 76 }; 77 78 struct psref_class * 79 psref_class_create(const char *, int); 80 void psref_class_destroy(struct psref_class *); 81 82 void psref_target_init(struct psref_target *, struct psref_class *); 83 void psref_target_destroy(struct psref_target *, struct psref_class *); 84 85 void psref_acquire(struct psref *, const struct psref_target *, 86 struct psref_class *); 87 void psref_release(struct psref *, const struct psref_target *, 88 struct psref_class *); 89 void psref_copy(struct psref *, const struct psref *, 90 struct psref_class *); 91 92 /* For use only in assertions. */ 93 bool psref_held(const struct psref_target *, struct psref_class *); 94 95 #endif /* _SYS_PSREF_H */ 96