about summary refs log tree commit diff
path: root/sysdeps/unix/sysv/linux/powerpc/elision-unlock.c
blob: 900a1073087b4e46e43ca2e9999c0608f22b0ed0 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
/* elision-unlock.c: Commit an elided pthread lock.
   Copyright (C) 2015-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include "pthreadP.h"
#include "lowlevellock.h"
#include "htm.h"

int
__lll_unlock_elision (int *lock, short *adapt_count, int pshared)
{
  /* When the lock was free we're in a transaction.  */
  if (*lock == 0)
    __libc_tend (0);
  else
    {
      /* Update adapt_count in the critical section to prevent a
	 write-after-destroy error as mentioned in BZ 20822.  The
	 following update of adapt_count has to be contained within
	 the critical region of the fall-back lock in order to not violate
	 the mutex destruction requirements.  */
      short __tmp = atomic_load_relaxed (adapt_count);
      if (__tmp > 0)
	atomic_store_relaxed (adapt_count, __tmp - 1);

      lll_unlock ((*lock), pshared);
    }
  return 0;
}