1 /* 2 * Copyright (c) 2014 Imre Vadász 3 * Copyright (c) 2014-2020 François Tigeot <ftigeot@wolfpond.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice unmodified, this list of conditions, and the following 11 * disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #ifndef _LINUX_WAIT_H_ 29 #define _LINUX_WAIT_H_ 30 31 #include <linux/list.h> 32 #include <linux/stddef.h> 33 #include <linux/spinlock.h> 34 #include <asm/current.h> 35 36 typedef struct __wait_queue wait_queue_t; 37 38 typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key); 39 40 int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key); 41 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key); 42 43 struct __wait_queue { 44 unsigned int flags; 45 void *private; 46 wait_queue_func_t func; 47 struct list_head task_list; 48 }; 49 50 typedef struct { 51 struct lock lock; 52 struct list_head task_list; 53 } wait_queue_head_t; 54 55 static inline void 56 init_waitqueue_head(wait_queue_head_t *eq) 57 { 58 lockinit(&eq->lock, "lwq", 0, LK_CANRECURSE); 59 INIT_LIST_HEAD(&eq->task_list); 60 } 61 62 void __wake_up_core(wait_queue_head_t *q, int num_to_wake_up); 63 64 static inline void 65 wake_up(wait_queue_head_t *q) 66 { 67 lockmgr(&q->lock, LK_EXCLUSIVE); 68 __wake_up_core(q, 1); 69 lockmgr(&q->lock, LK_RELEASE); 70 wakeup_one(q); 71 } 72 73 static inline void 74 wake_up_all(wait_queue_head_t *q) 75 { 76 lockmgr(&q->lock, LK_EXCLUSIVE); 77 __wake_up_core(q, 0); 78 lockmgr(&q->lock, LK_RELEASE); 79 wakeup(q); 80 } 81 82 #define wake_up_all_locked(eq) __wake_up_core(eq, 0) 83 84 #define wake_up_interruptible(eq) wake_up(eq) 85 #define wake_up_interruptible_all(eq) wake_up_all(eq) 86 87 void __wait_event_prefix(wait_queue_head_t *wq, int flags); 88 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait); 89 90 /* 91 * wait_event_interruptible_timeout: 92 * - The process is put to sleep until the condition evaluates to true. 93 * - The condition is checked each time the waitqueue wq is woken up. 94 * - wake_up has to be called after changing any variable that could change 95 * the result of the wait condition. 96 * 97 * returns: 98 * - 0 if the timeout elapsed 99 * - the remaining jiffies if the condition evaluated to true before 100 * the timeout elapsed. 101 * - remaining jiffies are always at least 1 102 * - -ERESTARTSYS if interrupted by a signal (when PCATCH is set in flags) 103 */ 104 #define __wait_event_common(wq, condition, timeout_jiffies, flags, \ 105 locked) \ 106 ({ \ 107 int start_jiffies, elapsed_jiffies, remaining_jiffies, ret; \ 108 bool timeout_expired = false; \ 109 bool interrupted = false; \ 110 long retval; \ 111 wait_queue_t tmp_wq; \ 112 \ 113 start_jiffies = ticks; \ 114 \ 115 while (1) { \ 116 __wait_event_prefix(&wq, flags); \ 117 \ 118 if (condition) \ 119 break; \ 120 \ 121 ret = tsleep(&wq, flags, "lwe", timeout_jiffies); \ 122 if (ret == EINTR || ret == ERESTART) { \ 123 interrupted = true; \ 124 break; \ 125 } \ 126 if (ret == EWOULDBLOCK) { \ 127 timeout_expired = true; \ 128 break; \ 129 } \ 130 } \ 131 \ 132 elapsed_jiffies = ticks - start_jiffies; \ 133 remaining_jiffies = timeout_jiffies - elapsed_jiffies; \ 134 if (remaining_jiffies <= 0) \ 135 remaining_jiffies = 1; \ 136 \ 137 if (timeout_expired) \ 138 retval = 0; \ 139 else if (interrupted) \ 140 retval = -ERESTARTSYS; \ 141 else if (timeout_jiffies > 0) \ 142 retval = remaining_jiffies; \ 143 else \ 144 retval = 1; \ 145 \ 146 finish_wait(&wq, &tmp_wq); \ 147 retval; \ 148 }) 149 150 #define wait_event(wq, condition) \ 151 __wait_event_common(wq, condition, 0, 0, false) 152 153 #define wait_event_timeout(wq, condition, timeout) \ 154 __wait_event_common(wq, condition, timeout, 0, false) 155 156 #define wait_event_interruptible(wq, condition) \ 157 ({ \ 158 long retval; \ 159 \ 160 retval = __wait_event_common(wq, condition, 0, PCATCH, false); \ 161 if (retval != -ERESTARTSYS) \ 162 retval = 0; \ 163 retval; \ 164 }) 165 166 #define wait_event_interruptible_locked(wq, condition) \ 167 ({ \ 168 long retval; \ 169 \ 170 retval = __wait_event_common(wq, condition, 0, PCATCH, true); \ 171 if (retval != -ERESTARTSYS) \ 172 retval = 0; \ 173 retval; \ 174 }) 175 176 #define wait_event_interruptible_timeout(wq, condition, timeout) \ 177 __wait_event_common(wq, condition, timeout, PCATCH, false) 178 179 static inline int 180 waitqueue_active(wait_queue_head_t *q) 181 { 182 return !list_empty(&q->task_list); 183 } 184 185 #define DEFINE_WAIT(name) \ 186 wait_queue_t name = { \ 187 .private = current, \ 188 .task_list = LIST_HEAD_INIT((name).task_list), \ 189 .func = autoremove_wake_function, \ 190 } 191 192 static inline void 193 prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state) 194 { 195 } 196 197 static inline void 198 __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new) 199 { 200 list_add(&new->task_list, &head->task_list); 201 } 202 203 static inline void 204 add_wait_queue(wait_queue_head_t *head, wait_queue_t *wq) 205 { 206 lockmgr(&head->lock, LK_EXCLUSIVE); 207 __add_wait_queue(head, wq); 208 lockmgr(&head->lock, LK_RELEASE); 209 } 210 211 #define DECLARE_WAIT_QUEUE_HEAD(name) \ 212 wait_queue_head_t name = { \ 213 .lock = LOCK_INITIALIZER("name", 0, LK_CANRECURSE), \ 214 .task_list = { &(name).task_list, &(name).task_list } \ 215 } 216 217 static inline void 218 __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old) 219 { 220 list_del(&old->task_list); 221 } 222 223 static inline void 224 remove_wait_queue(wait_queue_head_t *head, wait_queue_t *wq) 225 { 226 lockmgr(&head->lock, LK_EXCLUSIVE); 227 __remove_wait_queue(head, wq); 228 lockmgr(&head->lock, LK_RELEASE); 229 } 230 231 #endif /* _LINUX_WAIT_H_ */ 232