1 /* $NetBSD: psref.h,v 1.4 2019/05/17 03:34:27 ozaki-r 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 #ifdef _KERNEL_OPT 36 #include "opt_psref_debug.h" 37 #endif 38 39 #include <sys/types.h> 40 #include <sys/queue.h> 41 42 struct cpu_info; 43 struct lwp; 44 45 struct psref; 46 struct psref_class; 47 struct psref_target; 48 49 /* 50 * struct psref_target 51 * 52 * Bookkeeping for an object to which users can acquire passive 53 * references. This is compact so that it can easily be embedded 54 * into many multitudes of objects, e.g. IP packet flows. 55 * 56 * prt_draining is false on initialization, and may be written 57 * only once, to make it true, when someone has prevented new 58 * references from being created and wants to drain the target in 59 * order to destroy it. 60 */ 61 struct psref_target { 62 struct psref_class *prt_class; 63 bool prt_draining; 64 }; 65 66 /* 67 * struct psref 68 * 69 * Bookkeeping for a single passive reference. There should only 70 * be a few of these per CPU in the system at once, no matter how 71 * many targets are stored, so these are a bit larger than struct 72 * psref_target. The contents of struct psref may be read and 73 * written only on the local CPU. 74 */ 75 struct psref { 76 SLIST_ENTRY(psref) psref_entry; 77 void *psref_debug; /* For debugging */ 78 const struct psref_target *psref_target; 79 struct lwp *psref_lwp; 80 struct cpu_info *psref_cpu; 81 }; 82 83 #ifdef _KERNEL 84 void psref_init(void); 85 86 struct psref_class * 87 psref_class_create(const char *, int); 88 void psref_class_destroy(struct psref_class *); 89 90 void psref_target_init(struct psref_target *, struct psref_class *); 91 void psref_target_destroy(struct psref_target *, struct psref_class *); 92 93 void psref_acquire(struct psref *, const struct psref_target *, 94 struct psref_class *); 95 void psref_release(struct psref *, const struct psref_target *, 96 struct psref_class *); 97 void psref_copy(struct psref *, const struct psref *, 98 struct psref_class *); 99 100 /* For use only in assertions. */ 101 bool psref_held(const struct psref_target *, struct psref_class *); 102 103 104 #ifdef PSREF_DEBUG 105 void psref_debug_barrier(void); 106 void psref_debug_init_lwp(struct lwp *); 107 108 #define PSREF_DEBUG_BARRIER() psref_debug_barrier() 109 #define PSREF_DEBUG_INIT_LWP(l) psref_debug_init_lwp((l)) 110 #define PSREF_DEBUG_FILL_RETURN_ADDRESS0(psref, addr) do { \ 111 (psref)->psref_debug = (addr); \ 112 } while (0) 113 #define PSREF_DEBUG_FILL_RETURN_ADDRESS(psref) do { \ 114 PSREF_DEBUG_FILL_RETURN_ADDRESS0(psref, __builtin_return_address(0));\ 115 } while (0) 116 117 #else 118 119 #define PSREF_DEBUG_BARRIER() __nothing 120 #define PSREF_DEBUG_INIT_LWP(l) __nothing 121 #define PSREF_DEBUG_FILL_RETURN_ADDRESS0(psref, addr) __nothing 122 #define PSREF_DEBUG_FILL_RETURN_ADDRESS(psref) __nothing 123 124 #endif /* PSREF_DEBUG */ 125 126 #endif /* _KERNEL */ 127 128 #endif /* _SYS_PSREF_H */ 129