1 /* elision-lock.c: Elided pthread mutex lock.
2 Copyright (C) 2015-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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/>. */
22 #include <lowlevellock.h>
23 #include <elision-conf.h>
26 #if !defined(LLL_LOCK) && !defined(EXTRAARG)
27 /* Make sure the configuration code is always linked in for static
29 #include "elision-conf.c"
36 # define LLL_LOCK(a,b) lll_lock(a,b), 0
39 #define aconf __elision_aconf
41 /* Adaptive lock using transactions.
42 By default the lock region is run as a transaction, and when it
43 aborts or the lock is busy the lock adapts itself. */
46 __lll_lock_elision (int *lock
, short *adapt_count
, EXTRAARG
int pshared
)
53 for (int i
= aconf
.try_tbegin
; i
> 0; i
--)
55 if (__builtin_tbegin (0))
59 /* Lock was busy. Fall back to normal locking. */
60 __builtin_tabort (_ABORT_LOCK_BUSY
);
64 /* A persistent failure indicates that a retry will probably
65 result in another failure. Use normal locking now and
66 for the next couple of calls. */
67 if (_TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
69 if (aconf
.skip_lock_internal_abort
> 0)
70 *adapt_count
= aconf
.skip_lock_internal_abort
;
76 /* Fall back to locks for a bit if retries have been exhausted */
77 if (aconf
.try_tbegin
> 0 && aconf
.skip_lock_out_of_tbegin_retries
> 0)
78 *adapt_count
= aconf
.skip_lock_out_of_tbegin_retries
;
81 return LLL_LOCK ((*lock
), pshared
);