sysdeps/unix/sysv/linux/powerpc/elision-unlock.c

   1 /* elision-unlock.c: Commit an elided pthread lock.
   2    Copyright (C) 2015-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include "pthreadP.h"
  20 #include "lowlevellock.h"
  21 #include "htm.h"
  22
  23 int
  24 __lll_unlock_elision (int *lock, short *adapt_count, int pshared)
  25 {
  26 #ifndef __SPE__
  27   /* When the lock was free we're in a transaction.  */
  28   if (*lock == 0)
  29     __libc_tend (0);
  30   else
  31     {
  32       /* Update adapt_count in the critical section to prevent a
  33          write-after-destroy error as mentioned in BZ 20822.  The
  34          following update of adapt_count has to be contained within
  35          the critical region of the fall-back lock in order to not violate
  36          the mutex destruction requirements.  */
  37       short __tmp = atomic_load_relaxed (adapt_count);
  38       if (__tmp > 0)
  39         atomic_store_relaxed (adapt_count, __tmp - 1);
  40
  41       lll_unlock ((*lock), pshared);
  42     }
  43 #else
  44   lll_unlock ((*lock), pshared);
  45 #endif
  46   return 0;
  47 }