nptl/libc-cleanup.c

   1 /* Copyright (C) 2002-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   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
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include "pthreadP.h"
  20 #include <tls.h>
  21 #include <libc-lock.h>
  22
  23 void
  24 __libc_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer)
  25 {
  26   struct pthread *self = THREAD_SELF;
  27
  28   buffer->__prev = THREAD_GETMEM (self, cleanup);
  29
  30   int cancelhandling = THREAD_GETMEM (self, cancelhandling);
  31
  32   /* Disable asynchronous cancellation for now.  */
  33   if (__glibc_unlikely (cancelhandling & CANCELTYPE_BITMASK))
  34     while (1)
  35       {
  36         int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
  37                                                 cancelhandling
  38                                                 & ~CANCELTYPE_BITMASK,
  39                                                 cancelhandling);
  40         if (__glibc_likely (curval == cancelhandling))
  41           /* Successfully replaced the value.  */
  42           break;
  43
  44         /* Prepare for the next round.  */
  45         cancelhandling = curval;
  46       }
  47
  48   buffer->__canceltype = (cancelhandling & CANCELTYPE_BITMASK
  49                           ? PTHREAD_CANCEL_ASYNCHRONOUS
  50                           : PTHREAD_CANCEL_DEFERRED);
  51
  52   THREAD_SETMEM (self, cleanup, buffer);
  53 }
  54 libc_hidden_def (__libc_cleanup_push_defer)
  55
  56 void
  57 __libc_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer)
  58 {
  59   struct pthread *self = THREAD_SELF;
  60
  61   THREAD_SETMEM (self, cleanup, buffer->__prev);
  62
  63   int cancelhandling;
  64   if (__builtin_expect (buffer->__canceltype != PTHREAD_CANCEL_DEFERRED, 0)
  65       && ((cancelhandling = THREAD_GETMEM (self, cancelhandling))
  66           & CANCELTYPE_BITMASK) == 0)
  67     {
  68       while (1)
  69         {
  70           int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
  71                                                   cancelhandling
  72                                                   | CANCELTYPE_BITMASK,
  73                                                   cancelhandling);
  74           if (__glibc_likely (curval == cancelhandling))
  75             /* Successfully replaced the value.  */
  76             break;
  77
  78           /* Prepare for the next round.  */
  79           cancelhandling = curval;
  80         }
  81
  82       CANCELLATION_P (self);
  83     }
  84 }
  85 libc_hidden_def (__libc_cleanup_pop_restore)