sys/dev/drm/include/linux/wait.h

   1 /*
   2  * Copyright (c) 2014 François Tigeot
   3  * Copyright (c) 2014 Imre Vadász
   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 <sys/spinlock2.h>
  32 #include <sys/param.h>
  33
  34 typedef struct {
  35         struct spinlock lock;
  36 } wait_queue_head_t;
  37
  38 static inline void
  39 init_waitqueue_head(wait_queue_head_t *eq)
  40 {
  41         spin_init(&eq->lock, "linux_waitqueue");
  42 }
  43
  44 #define wake_up(eq)             wakeup_one(eq)
  45 #define wake_up_all(eq)         wakeup(eq)
  46
  47 /*
  48  * wait_event_interruptible_timeout:
  49  * - The process is put to sleep until the condition evaluates to true.
  50  * - The condition is checked each time the waitqueue wq is woken up.
  51  * - wake_up has to be called after changing any variable that could change
  52  * the result of the wait condition.
  53  *
  54  * returns:
  55  *   - 0 if the timeout elapsed
  56  *   - the remaining jiffies if the condition evaluated to true before
  57  *   the timeout elapsed.
  58  *   - remaining jiffies are always at least 1
  59  *   - -ERESTARTSYS if interrupted by a signal (when PCATCH is set in flags)
  60 */
  61 #define __wait_event_common(wq, condition, timeout_jiffies, flags)      \
  62 ({                                                                      \
  63         int start_jiffies, elapsed_jiffies, remaining_jiffies, ret;     \
  64         bool timeout_expired = false;                                   \
  65         bool interrupted = false;                                       \
  66         long retval;                                                    \
  67                                                                         \
  68         start_jiffies = ticks;                                          \
  69                                                                         \
  70         spin_lock(&wq.lock);                                            \
  71         while (1) {                                                     \
  72                 if (condition)                                          \
  73                         break;                                          \
  74                                                                         \
  75                 ret = ssleep(&wq, &wq.lock, flags,                      \
  76                                         "lwe", timeout_jiffies);        \
  77                 if (ret == EINTR || ret == ERESTART) {                  \
  78                         interrupted = true;                             \
  79                         break;                                          \
  80                 }                                                       \
  81                 if (ret == EWOULDBLOCK) {                               \
  82                         timeout_expired = true;                         \
  83                         break;                                          \
  84                 }                                                       \
  85         }                                                               \
  86         spin_unlock(&wq.lock);                                          \
  87                                                                         \
  88         elapsed_jiffies = ticks - start_jiffies;                        \
  89         remaining_jiffies = timeout_jiffies - elapsed_jiffies;          \
  90         if (remaining_jiffies <= 0)                                     \
  91                 remaining_jiffies = 1;                                  \
  92                                                                         \
  93         if (timeout_expired)                                            \
  94                 retval = 0;                                             \
  95         else if (interrupted)                                           \
  96                 retval = -ERESTARTSYS;                                  \
  97         else if (timeout_jiffies > 0)                                   \
  98                 retval = remaining_jiffies;                             \
  99         else                                                            \
 100                 retval = 1;                                             \
 101                                                                         \
 102         retval;                                                         \
 103 })
 104
 105 #define wait_event(wq, condition)                                       \
 106                 __wait_event_common(wq, condition, 0, 0)
 107
 108 #define wait_event_timeout(wq, condition, timeout)                      \
 109                 __wait_event_common(wq, condition, timeout, 0)
 110
 111 #define wait_event_interruptible(wq, condition)                         \
 112 ({                                                                      \
 113         long retval;                                                    \
 114                                                                         \
 115         retval = __wait_event_common(wq, condition, 0, PCATCH);         \
 116         if (retval != -ERESTARTSYS)                                     \
 117                 retval = 0;                                             \
 118         retval;                                                         \
 119 })
 120
 121 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 122                 __wait_event_common(wq, condition, timeout, PCATCH)
 123
 124 #endif  /* _LINUX_WAIT_H_ */