1 /* 2 * Copyright (c) 2019-2020 François Tigeot <ftigeot@wolfpond.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <linux/wait.h> 28 #include <linux/wait_bit.h> 29 #include <linux/sched.h> 30 31 int 32 default_wake_function(wait_queue_entry_t *q, unsigned mode, int wake_flags, void *key) 33 { 34 return wake_up_process(q->private); 35 } 36 37 int 38 autoremove_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) 39 { 40 int ret = default_wake_function(wait, mode, sync, key); 41 42 /* Was the process woken up ? */ 43 if (ret) 44 list_del_init(&wait->entry); 45 46 return ret; 47 } 48 49 void 50 __wake_up_core(wait_queue_head_t *q, int num_to_wake_up) 51 { 52 wait_queue_entry_t *curr, *next; 53 int mode = TASK_NORMAL; 54 55 list_for_each_entry_safe(curr, next, &q->head, entry) { 56 if (curr->func(curr, mode, 0, NULL)) 57 num_to_wake_up--; 58 59 if (num_to_wake_up == 0) 60 break; 61 } 62 } 63 64 void 65 __wait_event_prefix(wait_queue_head_t *wq, int flags) 66 { 67 lockmgr(&wq->lock, LK_EXCLUSIVE); 68 if (flags & PCATCH) { 69 set_current_state(TASK_INTERRUPTIBLE); 70 } else { 71 set_current_state(TASK_UNINTERRUPTIBLE); 72 } 73 lockmgr(&wq->lock, LK_RELEASE); 74 } 75 76 void 77 prepare_to_wait(wait_queue_head_t *q, wait_queue_entry_t *wait, int state) 78 { 79 lockmgr(&q->lock, LK_EXCLUSIVE); 80 if (list_empty(&wait->entry)) 81 __add_wait_queue(q, wait); 82 set_current_state(state); 83 lockmgr(&q->lock, LK_RELEASE); 84 } 85 86 void 87 finish_wait(wait_queue_head_t *q, wait_queue_entry_t *wait) 88 { 89 set_current_state(TASK_RUNNING); 90 91 lockmgr(&q->lock, LK_EXCLUSIVE); 92 if (!list_empty(&wait->entry)) 93 list_del_init(&wait->entry); 94 lockmgr(&q->lock, LK_RELEASE); 95 } 96 97 void 98 wake_up_bit(void *addr, int bit) 99 { 100 wakeup_one(addr); 101 } 102 103 /* Wait for a bit to be cleared or a timeout to expire */ 104 int 105 wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode, 106 unsigned long timeout) 107 { 108 int rv, awakened = 0, timeout_expired = 0; 109 long start_time; 110 111 if (!test_bit(bit, word)) 112 return 0; 113 114 start_time = ticks; 115 set_current_state(mode); 116 117 do { 118 rv = tsleep(word, mode, "lwobt", timeout); 119 if (rv == 0) 120 awakened = 1; 121 if (time_after_eq(start_time, timeout)) 122 timeout_expired = 1; 123 } while (test_bit(bit, word) && !timeout_expired); 124 125 set_current_state(TASK_RUNNING); 126 127 if (awakened) 128 return 0; 129 130 return 1; 131 } 132 133 void __init_waitqueue_head(wait_queue_head_t *q, 134 const char *name, struct lock_class_key *key) 135 { 136 lockinit(&q->lock, "lwq", 0, 0); 137 INIT_LIST_HEAD(&q->head); 138 } 139 140 int 141 wait_on_bit(unsigned long *word, int bit, unsigned mode) 142 { 143 return wait_on_bit_timeout(word, bit, mode, MAX_SCHEDULE_TIMEOUT); 144 } 145 146 void 147 init_wait_entry(struct wait_queue_entry *wq_entry, int flags) 148 { 149 INIT_LIST_HEAD(&wq_entry->entry); 150 wq_entry->flags = flags; 151 wq_entry->private = current; 152 wq_entry->func = autoremove_wake_function; 153 } 154