libgcc/config/gthr-vxworks.c

   1 /* Copyright (C) 2002-2020 Free Software Foundation, Inc.
   2    Contributed by Zack Weinberg <zack@codesourcery.com>
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 Under Section 7 of GPL version 3, you are granted additional
  17 permissions described in the GCC Runtime Library Exception, version
  18 3.1, as published by the Free Software Foundation.
  19
  20 You should have received a copy of the GNU General Public License and
  21 a copy of the GCC Runtime Library Exception along with this program;
  22 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 <http://www.gnu.org/licenses/>.  */
  24
  25 /* Threads compatibility routines for libgcc2 for VxWorks.
  26
  27    This file implements the init-once service exposed by gthr-vxworks.h.  */
  28
  29 #include "tconfig.h"
  30 #include "tsystem.h"
  31 #include "gthr.h"
  32
  33 #if defined(__GTHREADS)
  34
  35 #include <vxWorks.h>
  36 #include <taskLib.h>
  37
  38 #ifndef __RTP__
  39 # include <vxLib.h>
  40 # include <taskHookLib.h>
  41 #else /* __RTP__ */
  42 # include <errno.h>
  43 #endif /* __RTP__ */
  44
  45 /* ----------------------------- Init-once ------------------------------- */
  46
  47 static void
  48 __release (__gthread_once_t ** __guard)
  49 {
  50   (*__guard)->busy = 0;
  51 }
  52
  53 int
  54 __gthread_once (__gthread_once_t * __guard, void (*__func) (void))
  55 {
  56   if (__guard->done)
  57     return 0;
  58
  59   /* Busy-wait until we have exclusive access to the state.  Check if
  60      another thread managed to perform the init call in the interim.  */
  61
  62   while (!__TAS(&__guard->busy))
  63     {
  64       if (__guard->done)
  65         return 0;
  66       taskDelay (1);
  67     }
  68
  69   if (!__guard->done)
  70     {
  71 #ifndef __USING_SJLJ_EXCEPTIONS__
  72       /* Setup a cleanup to release the guard when __func() throws an
  73          exception.  We cannot use this with SJLJ exceptions as
  74          Unwind_Register calls __gthread_once, leading to an infinite
  75          recursion.  */
  76       __attribute__ ((cleanup (__release)))
  77         __gthread_once_t *__temp = __guard;
  78 #endif
  79
  80       __func ();
  81       __guard->done = 1;
  82     }
  83
  84   __release(&__guard);
  85   return 0;
  86 }
  87
  88 #endif /* __GTHREADS */