1 /* elision-unlock.c: Commit an elided pthread lock.
2 Copyright (C) 2015-2022 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
__lll_unlock_elision(int * lock,short * adapt_count,int pshared)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)
45