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

   1 /* Copyright (C) 2003-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation; either version 2.1 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If
  16    not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <pthread.h>
  19 #include <setjmp.h>
  20 #include <signal.h>
  21 #include <sys/types.h>
  22
  23
  24 /* Nonzero if the system calls are not available.  */
  25 extern int __no_posix_timers attribute_hidden;
  26
  27 /* Callback to start helper thread.  */
  28 extern void __timer_start_helper_thread (void) attribute_hidden;
  29
  30 /* Control variable for helper thread creation.  */
  31 extern pthread_once_t __timer_helper_once attribute_hidden;
  32
  33 /* Called from fork so that the new subprocess re-creates the
  34    notification thread if necessary.  */
  35 void __timer_fork_subprocess (void) attribute_hidden;
  36
  37 /* TID of the helper thread.  */
  38 extern pid_t __timer_helper_tid attribute_hidden;
  39
  40 /* List of active SIGEV_THREAD timers.  */
  41 extern struct timer *__timer_active_sigev_thread attribute_hidden;
  42
  43 /* Lock for __timer_active_sigev_thread.  */
  44 extern pthread_mutex_t __timer_active_sigev_thread_lock attribute_hidden;
  45
  46 extern __typeof (timer_create) __timer_create;
  47 libc_hidden_proto (__timer_create)
  48 extern __typeof (timer_delete) __timer_delete;
  49 libc_hidden_proto (__timer_delete)
  50 extern __typeof (timer_getoverrun) __timer_getoverrun;
  51 libc_hidden_proto (__timer_getoverrun)
  52
  53 /* Type of timers in the kernel.  */
  54 typedef int kernel_timer_t;
  55
  56 /* Internal representation of SIGEV_THREAD timer.  */
  57 struct timer
  58 {
  59   kernel_timer_t ktimerid;
  60
  61   void (*thrfunc) (sigval_t);
  62   sigval_t sival;
  63   pthread_attr_t attr;
  64
  65   /* Next element in list of active SIGEV_THREAD timers.  */
  66   struct timer *next;
  67 };
  68
  69
  70 /* For !SIGEV_THREAD, the resulting 'timer_t' is the returned kernel timer
  71    identifier (kernel_timer_t), while for SIGEV_THREAD it uses the fact malloc
  72    returns at least _Alignof (max_align_t) pointers plus that valid
  73    kernel_timer_t are always positive to set the MSB bit of the returned
  74    'timer_t' to indicate the timer handles a SIGEV_THREAD.  */
  75
  76 static inline timer_t
  77 kernel_timer_to_timerid (kernel_timer_t ktimerid)
  78 {
  79   return (timer_t) ((intptr_t) ktimerid);
  80 }
  81
  82 static inline timer_t
  83 timer_to_timerid (struct timer *ptr)
  84 {
  85   return (timer_t) (INTPTR_MIN | (uintptr_t) ptr >> 1);
  86 }
  87
  88 static inline bool
  89 timer_is_sigev_thread (timer_t timerid)
  90 {
  91   return (intptr_t) timerid < 0;
  92 }
  93
  94 static inline struct timer *
  95 timerid_to_timer (timer_t timerid)
  96 {
  97   return (struct timer *)((uintptr_t) timerid << 1);
  98 }
  99
 100 static inline kernel_timer_t
 101 timerid_to_kernel_timer (timer_t timerid)
 102 {
 103   if (timer_is_sigev_thread (timerid))
 104     return timerid_to_timer (timerid)->ktimerid;
 105   else
 106     return (kernel_timer_t) ((uintptr_t) timerid);
 107 }
 108
 109 /* New targets use int instead of timer_t.  The difference only
 110    matters on 64-bit targets.  */
 111 #include <timer_t_was_int_compat.h>
 112
 113 #if TIMER_T_WAS_INT_COMPAT
 114 # define OLD_TIMER_MAX 256
 115 extern timer_t __timer_compat_list[OLD_TIMER_MAX];
 116 #endif