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 | |