sysdeps/unix/sysv/linux/kernel-posix-timers.h

   1 /* Copyright (C) 2003-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #include <pthread.h>
  20 #include <setjmp.h>
  21 #include <signal.h>
  22 #include <sys/types.h>
  23
  24
  25 /* Nonzero if the system calls are not available.  */
  26 extern int __no_posix_timers attribute_hidden;
  27
  28 /* Callback to start helper thread.  */
  29 extern void __start_helper_thread (void) attribute_hidden;
  30
  31 /* Control variable for helper thread creation.  */
  32 extern pthread_once_t __helper_once attribute_hidden;
  33
  34 /* TID of the helper thread.  */
  35 extern pid_t __helper_tid attribute_hidden;
  36
  37 /* List of active SIGEV_THREAD timers.  */
  38 extern struct timer *__active_timer_sigev_thread attribute_hidden;
  39 /* Lock for the __active_timer_sigev_thread.  */
  40 extern pthread_mutex_t __active_timer_sigev_thread_lock attribute_hidden;
  41
  42
  43 /* Type of timers in the kernel.  */
  44 typedef int kernel_timer_t;
  45
  46 /* Internal representation of SIGEV_THREAD timer.  */
  47 struct timer
  48 {
  49   kernel_timer_t ktimerid;
  50
  51   void (*thrfunc) (sigval_t);
  52   sigval_t sival;
  53   pthread_attr_t attr;
  54
  55   /* Next element in list of active SIGEV_THREAD timers.  */
  56   struct timer *next;
  57 };
  58
  59
  60 /* For !SIGEV_THREAD, the resulting 'timer_t' is the returned kernel timer
  61    identifer (kernel_timer_t), while for SIGEV_THREAD it uses the fact malloc
  62    returns at least _Alignof (max_align_t) pointers plus that valid
  63    kernel_timer_t are always positive to set the MSB bit of the returned
  64    'timer_t' to indicate the timer handles a SIGEV_THREAD.  */
  65
  66 static inline timer_t
  67 kernel_timer_to_timerid (kernel_timer_t ktimerid)
  68 {
  69   return (timer_t) ((intptr_t) ktimerid);
  70 }
  71
  72 static inline timer_t
  73 timer_to_timerid (struct timer *ptr)
  74 {
  75   return (timer_t) (INTPTR_MIN | (uintptr_t) ptr >> 1);
  76 }
  77
  78 static inline bool
  79 timer_is_sigev_thread (timer_t timerid)
  80 {
  81   return (intptr_t) timerid < 0;
  82 }
  83
  84 static inline struct timer *
  85 timerid_to_timer (timer_t timerid)
  86 {
  87   return (struct timer *)((uintptr_t) timerid << 1);
  88 }
  89
  90 static inline kernel_timer_t
  91 timerid_to_kernel_timer (timer_t timerid)
  92 {
  93   if (timer_is_sigev_thread (timerid))
  94     return timerid_to_timer (timerid)->ktimerid;
  95   else
  96     return (kernel_timer_t) ((uintptr_t) timerid);
  97 }