1  /* elision-unlock.c: Commit an elided pthread lock.
       2     Copyright (C) 2015-2023 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)