1 /* 2 * Copyright (c) 2014-2017 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 #ifndef _LINUX_COMPLETION_H_ 27 #define _LINUX_COMPLETION_H_ 28 29 #include <linux/wait.h> 30 #include <linux/errno.h> 31 32 struct completion { 33 unsigned int done; 34 wait_queue_head_t wait; 35 }; 36 37 static inline void 38 init_completion(struct completion *c) 39 { 40 c->done = 0; 41 init_waitqueue_head(&c->wait); 42 } 43 44 static inline void 45 reinit_completion(struct completion *c) 46 { 47 c->done = 0; 48 } 49 50 #define INIT_COMPLETION(c) (c.done = 0) 51 52 /* 53 * Completion interlock and wakeup. Be careful not to execute the wakeup 54 * from inside the spinlock as this can deadlock if the IPIQ fifo is full. 55 * (also note that wakeup() is asynchronous anyway, so no point doing that). 56 */ 57 static inline void 58 complete(struct completion *c) 59 { 60 lockmgr(&c->wait.lock, LK_EXCLUSIVE); 61 c->done++; 62 lockmgr(&c->wait.lock, LK_RELEASE); 63 wakeup_one(&c->wait); 64 } 65 66 static inline void 67 complete_all(struct completion *c) 68 { 69 lockmgr(&c->wait.lock, LK_EXCLUSIVE); 70 c->done++; 71 lockmgr(&c->wait.lock, LK_RELEASE); 72 wakeup(&c->wait); 73 } 74 75 static inline long 76 __wait_for_completion_generic(struct completion *c, 77 unsigned long timeout, int flags) 78 { 79 int start_jiffies, elapsed_jiffies, remaining_jiffies; 80 bool timeout_expired = false, awakened = false; 81 long ret = 1; 82 83 start_jiffies = ticks; 84 85 lockmgr(&c->wait.lock, LK_EXCLUSIVE); 86 while (c->done == 0 && !timeout_expired) { 87 ret = lksleep(&c->wait, &c->wait.lock, flags, "lwfcg", timeout); 88 switch(ret) { 89 case EWOULDBLOCK: 90 timeout_expired = true; 91 ret = 0; 92 break; 93 case ERESTART: 94 ret = -ERESTARTSYS; 95 break; 96 case 0: 97 awakened = true; 98 break; 99 } 100 } 101 lockmgr(&c->wait.lock, LK_RELEASE); 102 103 if (awakened) { 104 elapsed_jiffies = ticks - start_jiffies; 105 remaining_jiffies = timeout - elapsed_jiffies; 106 if (remaining_jiffies > 0) 107 ret = remaining_jiffies; 108 } 109 110 return ret; 111 } 112 113 static inline long 114 wait_for_completion_interruptible_timeout(struct completion *c, 115 unsigned long timeout) 116 { 117 return __wait_for_completion_generic(c, timeout, PCATCH); 118 } 119 120 static inline unsigned long 121 wait_for_completion_timeout(struct completion *c, unsigned long timeout) 122 { 123 return __wait_for_completion_generic(c, timeout, 0); 124 } 125 126 /* 127 * try_wait_for_completion: try to decrement a completion without blocking 128 * its thread 129 * return: false if the completion thread would need to be blocked/queued 130 * true if a non-blocking decrement was successful 131 */ 132 static inline bool 133 try_wait_for_completion(struct completion *c) 134 { 135 bool ret = false; 136 137 /* we can't decrement c->done below 0 */ 138 if (READ_ONCE(c->done) == 0) 139 return false; 140 141 lockmgr(&c->wait.lock, LK_EXCLUSIVE); 142 if (c->done > 0) { 143 c->done--; 144 ret = true; 145 } 146 lockmgr(&c->wait.lock, LK_RELEASE); 147 148 return ret; 149 } 150 151 #endif /* _LINUX_COMPLETION_H_ */ 152