1 | /* $NetBSD: completion.h,v 1.5 2014/09/02 09:54:20 jmcneill Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (c) 2013 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 | /* |
33 | * Notes on porting: |
34 | * |
35 | * - Linux does not have destroy_completion. You must add it yourself |
36 | * in the appropriate place. |
37 | * |
38 | * - Some Linux code does `completion->done++' or similar. Convert |
39 | * that to complete(completion) and suggest the same change upstream, |
40 | * unless it turns out there actually is a good reason to do that, in |
41 | * which case the Linux completion API should be extended with a |
42 | * sensible name for this that doesn't expose the guts of `struct |
43 | * completion'. |
44 | */ |
45 | |
46 | #ifndef _LINUX_COMPLETION_H_ |
47 | #define _LINUX_COMPLETION_H_ |
48 | |
49 | #include <sys/types.h> |
50 | #include <sys/condvar.h> |
51 | #include <sys/mutex.h> |
52 | |
53 | #include <machine/limits.h> |
54 | |
55 | #include <linux/errno.h> |
56 | |
57 | struct completion { |
58 | kmutex_t c_lock; |
59 | kcondvar_t c_cv; |
60 | |
61 | /* |
62 | * c_done is either |
63 | * |
64 | * . -1, meaning it's open season and we're done for good and |
65 | * nobody need wait any more; |
66 | * |
67 | * . 0, meaning nothing is done, so waiters must block; or |
68 | * |
69 | * . a positive integer, meaning that many waiters can |
70 | * proceed before further waiters must block. |
71 | * |
72 | * Negative values other than -1 are not allowed. |
73 | */ |
74 | int c_done; |
75 | }; |
76 | |
77 | /* |
78 | * Initialize a new completion object. |
79 | */ |
80 | static inline void |
81 | init_completion(struct completion *completion) |
82 | { |
83 | |
84 | mutex_init(&completion->c_lock, MUTEX_DEFAULT, IPL_SCHED); |
85 | cv_init(&completion->c_cv, "lnxcmplt" ); |
86 | completion->c_done = 0; |
87 | } |
88 | |
89 | /* |
90 | * Destroy a completion object. |
91 | */ |
92 | static inline void |
93 | destroy_completion(struct completion *completion) |
94 | { |
95 | KASSERT(!cv_has_waiters(&completion->c_cv)); |
96 | cv_destroy(&completion->c_cv); |
97 | mutex_destroy(&completion->c_lock); |
98 | } |
99 | |
100 | /* |
101 | * Notify one waiter of completion, but not any future ones. |
102 | */ |
103 | static inline void |
104 | complete(struct completion *completion) |
105 | { |
106 | |
107 | mutex_enter(&completion->c_lock); |
108 | |
109 | /* If it's not open season, wake one waiter. */ |
110 | if (completion->c_done >= 0) { |
111 | KASSERT(completion->c_done < INT_MAX); /* XXX check */ |
112 | completion->c_done++; |
113 | cv_signal(&completion->c_cv); |
114 | } else { |
115 | KASSERT(completion->c_done == -1); |
116 | } |
117 | |
118 | mutex_exit(&completion->c_lock); |
119 | } |
120 | |
121 | /* |
122 | * Notify all waiters, present and future (until INIT_COMPLETION), of |
123 | * completion. |
124 | */ |
125 | static inline void |
126 | complete_all(struct completion *completion) |
127 | { |
128 | |
129 | mutex_enter(&completion->c_lock); |
130 | |
131 | /* If it's not open season, make it open season and wake everyone. */ |
132 | if (completion->c_done >= 0) { |
133 | completion->c_done = -1; |
134 | cv_broadcast(&completion->c_cv); |
135 | } else { |
136 | KASSERT(completion->c_done == -1); |
137 | } |
138 | |
139 | mutex_exit(&completion->c_lock); |
140 | } |
141 | |
142 | /* |
143 | * Reverse the effect of complete_all so that subsequent waiters block |
144 | * until someone calls complete or complete_all. |
145 | * |
146 | * This operation is very different from its lowercase counterpart. |
147 | * |
148 | * For some reason this works on the completion object itself, not on a |
149 | * pointer thereto, so it must be a macro. |
150 | */ |
151 | #define INIT_COMPLETION(COMPLETION) INIT_COMPLETION_blorp(&(COMPLETION)) |
152 | |
153 | static inline void |
154 | INIT_COMPLETION_blorp(struct completion *completion) |
155 | { |
156 | |
157 | mutex_enter(&completion->c_lock); |
158 | completion->c_done = 0; |
159 | /* No notify -- waiters are interested only in nonzero values. */ |
160 | mutex_exit(&completion->c_lock); |
161 | } |
162 | |
163 | static inline void |
164 | _completion_claim(struct completion *completion) |
165 | { |
166 | |
167 | KASSERT(mutex_owned(&completion->c_lock)); |
168 | KASSERT(completion->c_done != 0); |
169 | if (completion->c_done > 0) |
170 | completion->c_done--; |
171 | else |
172 | KASSERT(completion->c_done == -1); |
173 | } |
174 | |
175 | /* |
176 | * Wait interruptibly with a timeout for someone to call complete or |
177 | * complete_all. |
178 | */ |
179 | static inline int |
180 | wait_for_completion_interruptible_timeout(struct completion *completion, |
181 | unsigned long ticks) |
182 | { |
183 | /* XXX Arithmetic overflow...? */ |
184 | unsigned int start = hardclock_ticks, now; |
185 | int error; |
186 | |
187 | mutex_enter(&completion->c_lock); |
188 | |
189 | /* Wait until c_done is nonzero. */ |
190 | while (completion->c_done == 0) { |
191 | error = cv_timedwait_sig(&completion->c_cv, |
192 | &completion->c_lock, ticks); |
193 | if (error) |
194 | goto out; |
195 | now = hardclock_ticks; |
196 | if (ticks < (now - start)) { |
197 | error = EWOULDBLOCK; |
198 | goto out; |
199 | } |
200 | ticks -= (now - start); |
201 | start = now; |
202 | } |
203 | |
204 | /* Success! */ |
205 | _completion_claim(completion); |
206 | error = 0; |
207 | |
208 | out: mutex_exit(&completion->c_lock); |
209 | if (error == EWOULDBLOCK) { |
210 | return 0; |
211 | } else if ((error == EINTR) || (error == ERESTART)) { |
212 | return -ERESTARTSYS; |
213 | } else { |
214 | KASSERTMSG((error == 0), "error = %d" , error); |
215 | return ticks; |
216 | } |
217 | } |
218 | |
219 | /* |
220 | * Wait interruptibly for someone to call complete or complete_all. |
221 | */ |
222 | static inline int |
223 | wait_for_completion_interruptible(struct completion *completion) |
224 | { |
225 | int error; |
226 | |
227 | mutex_enter(&completion->c_lock); |
228 | |
229 | /* Wait until c_done is nonzero. */ |
230 | while (completion->c_done == 0) { |
231 | error = cv_wait_sig(&completion->c_cv, &completion->c_lock); |
232 | if (error) |
233 | goto out; |
234 | } |
235 | |
236 | /* Success! */ |
237 | _completion_claim(completion); |
238 | error = 0; |
239 | |
240 | out: mutex_exit(&completion->c_lock); |
241 | if ((error == EINTR) || (error == ERESTART)) |
242 | error = -ERESTARTSYS; |
243 | return error; |
244 | } |
245 | |
246 | /* |
247 | * Wait uninterruptibly, except by SIGKILL, for someone to call |
248 | * complete or complete_all. |
249 | * |
250 | * XXX In this implementation, any signal will actually wake us, not |
251 | * just SIGKILL. |
252 | */ |
253 | static inline int |
254 | wait_for_completion_killable(struct completion *completion) |
255 | { |
256 | |
257 | return wait_for_completion_interruptible(completion); |
258 | } |
259 | |
260 | /* |
261 | * Try to claim a completion immediately. Return true on success, false |
262 | * if it would block. |
263 | */ |
264 | static inline bool |
265 | try_wait_for_completion(struct completion *completion) |
266 | { |
267 | bool ok; |
268 | |
269 | mutex_enter(&completion->c_lock); |
270 | if (completion->c_done == 0) { |
271 | ok = false; |
272 | } else { |
273 | _completion_claim(completion); |
274 | ok = true; |
275 | } |
276 | mutex_exit(&completion->c_lock); |
277 | |
278 | return ok; |
279 | } |
280 | |
281 | #endif /* _LINUX_COMPLETION_H_ */ |
282 | |