src/linux/thread.c

   1 /*****************************************************************************
   2  * linux/thread.c: Linux specifics for threading
   3  *****************************************************************************
   4  * Copyright (C) 2016 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include "config.h"
  23 #endif
  24
  25 #include <assert.h>
  26 #include <errno.h>
  27 #include <limits.h>
  28 #include <stdlib.h>
  29 #include <sys/types.h>
  30 #include <unistd.h>
  31 #include <sys/syscall.h>
  32 #include <linux/futex.h>
  33
  34 #ifndef FUTEX_PRIVATE_FLAG
  35 #define FUTEX_WAKE_PRIVATE FUTEX_WAKE
  36 #define FUTEX_WAIT_PRIVATE FUTEX_WAIT
  37 #define FUTEX_WAIT_BITSET_PRIVATE FUTEX_WAIT_BITSET
  38 #endif
  39
  40 #include <vlc_common.h>
  41
  42 unsigned long vlc_thread_id(void)
  43 {
  44      static __thread pid_t tid = 0;
  45
  46      if (unlikely(tid == 0))
  47          tid = syscall(__NR_gettid);
  48
  49      return tid;
  50 }
  51
  52 static int sys_futex(void *addr, int op, unsigned val,
  53                      const struct timespec *to, void *addr2, int val3)
  54 {
  55     return syscall(__NR_futex, addr, op, val, to, addr2, val3);
  56 }
  57
  58 static int vlc_futex_wake(void *addr, int nr)
  59 {
  60     return sys_futex(addr, FUTEX_WAKE_PRIVATE, nr, NULL, NULL, 0);
  61 }
  62
  63 static int vlc_futex_wait(void *addr, unsigned flags,
  64                           unsigned val, const struct timespec *to)
  65 {
  66     return sys_futex(addr, FUTEX_WAIT_BITSET_PRIVATE | flags, val, to, NULL,
  67                      FUTEX_BITSET_MATCH_ANY);
  68 }
  69
  70 void vlc_atomic_notify_one(void *addr)
  71 {
  72     vlc_futex_wake(addr, 1);
  73 }
  74
  75 void vlc_atomic_notify_all(void *addr)
  76 {
  77     vlc_futex_wake(addr, INT_MAX);
  78 }
  79
  80 void vlc_atomic_wait(void *addr, unsigned val)
  81 {
  82     vlc_futex_wait(addr, 0, val, NULL);
  83 }
  84
  85 int vlc_atomic_timedwait(void *addr, unsigned val, vlc_tick_t deadline)
  86 {
  87     struct timespec ts = timespec_from_vlc_tick(deadline);
  88
  89     if (vlc_futex_wait(addr, 0, val, &ts) == 0)
  90         return 0;
  91
  92     switch (errno) {
  93         case EINTR:
  94         case EAGAIN:
  95             return 0;
  96         case EFAULT:
  97         case EINVAL:
  98             vlc_assert_unreachable(); /* BUG! */
  99         default:
 100             break;
 101      }
 102      return errno;
 103 }
 104
 105 int vlc_atomic_timedwait_daytime(void *addr, unsigned val, time_t deadline)
 106 {
 107     struct timespec ts = { .tv_sec = deadline, .tv_nsec = 0 };
 108
 109     if (vlc_futex_wait(addr, FUTEX_CLOCK_REALTIME, val, &ts) == 0)
 110         return 0;
 111
 112     switch (errno) {
 113         case EINTR:
 114         case EAGAIN:
 115             return 0;
 116         case EFAULT:
 117         case EINVAL:
 118             vlc_assert_unreachable(); /* BUG! */
 119         default:
 120             break;
 121      }
 122      return errno;
 123 }