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

   1 /* elision-unlock.c: Commit an elided pthread lock.
   2    Copyright (C) 2015-2021 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    <https://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   /* When the lock was free we're in a transaction.  */
  27   if (*lock == 0)
  28     __libc_tend (0);
  29   else
  30     {
  31       /* Update adapt_count in the critical section to prevent a
  32          write-after-destroy error as mentioned in BZ 20822.  The
  33          following update of adapt_count has to be contained within
  34          the critical region of the fall-back lock in order to not violate
  35          the mutex destruction requirements.  */
  36       short __tmp = atomic_load_relaxed (adapt_count);
  37       if (__tmp > 0)
  38         atomic_store_relaxed (adapt_count, __tmp - 1);
  39
  40       lll_unlock ((*lock), pshared);
  41     }
  42   return 0;
  43 }
  44 libc_hidden_def (__lll_unlock_elision)