| 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 | |