nptl/cleanup_defer.c

   1 /* Copyright (C) 2002-2020 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 <stdlib.h>
  20 #include "pthreadP.h"
  21
  22
  23 void
  24 __cleanup_fct_attribute
  25 __pthread_register_cancel_defer (__pthread_unwind_buf_t *buf)
  26 {
  27   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
  28   struct pthread *self = THREAD_SELF;
  29
  30   /* Store old info.  */
  31   ibuf->priv.data.prev = THREAD_GETMEM (self, cleanup_jmp_buf);
  32   ibuf->priv.data.cleanup = THREAD_GETMEM (self, cleanup);
  33
  34   int cancelhandling = THREAD_GETMEM (self, cancelhandling);
  35
  36   /* Disable asynchronous cancellation for now.  */
  37   if (__glibc_unlikely (cancelhandling & CANCELTYPE_BITMASK))
  38     while (1)
  39       {
  40         int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
  41                                                 cancelhandling
  42                                                 & ~CANCELTYPE_BITMASK,
  43                                                 cancelhandling);
  44         if (__glibc_likely (curval == cancelhandling))
  45           /* Successfully replaced the value.  */
  46           break;
  47
  48         /* Prepare for the next round.  */
  49         cancelhandling = curval;
  50       }
  51
  52   ibuf->priv.data.canceltype = (cancelhandling & CANCELTYPE_BITMASK
  53                                 ? PTHREAD_CANCEL_ASYNCHRONOUS
  54                                 : PTHREAD_CANCEL_DEFERRED);
  55
  56   /* Store the new cleanup handler info.  */
  57   THREAD_SETMEM (self, cleanup_jmp_buf, (struct pthread_unwind_buf *) buf);
  58 }
  59
  60
  61 void
  62 __cleanup_fct_attribute
  63 __pthread_unregister_cancel_restore (__pthread_unwind_buf_t *buf)
  64 {
  65   struct pthread *self = THREAD_SELF;
  66   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
  67
  68   THREAD_SETMEM (self, cleanup_jmp_buf, ibuf->priv.data.prev);
  69
  70   int cancelhandling;
  71   if (ibuf->priv.data.canceltype != PTHREAD_CANCEL_DEFERRED
  72       && ((cancelhandling = THREAD_GETMEM (self, cancelhandling))
  73           & CANCELTYPE_BITMASK) == 0)
  74     {
  75       while (1)
  76         {
  77           int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
  78                                                   cancelhandling
  79                                                   | CANCELTYPE_BITMASK,
  80                                                   cancelhandling);
  81           if (__glibc_likely (curval == cancelhandling))
  82             /* Successfully replaced the value.  */
  83             break;
  84
  85           /* Prepare for the next round.  */
  86           cancelhandling = curval;
  87         }
  88
  89       CANCELLATION_P (self);
  90     }
  91 }