powerpc: Enforce compiler barriers on hardware transactions
[glibc.git] / sysdeps / unix / sysv / linux / powerpc / elision-lock.c
blobdd1e4c3b17a362fdc12cc04f9daf9ae4ac2c6204
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/>. */
19 #include <stdio.h>
20 #include <pthread.h>
21 #include <pthreadP.h>
22 #include <lowlevellock.h>
23 #include <elision-conf.h>
24 #include "htm.h"
26 #if !defined(LLL_LOCK) && !defined(EXTRAARG)
27 /* Make sure the configuration code is always linked in for static
28 libraries. */
29 #include "elision-conf.c"
30 #endif
32 #ifndef EXTRAARG
33 # define EXTRAARG
34 #endif
35 #ifndef LLL_LOCK
36 # define LLL_LOCK(a,b) lll_lock(a,b), 0
37 #endif
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. */
45 int
46 __lll_lock_elision (int *lock, short *adapt_count, EXTRAARG int pshared)
48 if (*adapt_count > 0)
50 goto use_lock;
53 for (int i = aconf.try_tbegin; i > 0; i--)
55 if (__libc_tbegin (0))
57 if (*lock == 0)
58 return 0;
59 /* Lock was busy. Fall back to normal locking. */
60 __libc_tabort (_ABORT_LOCK_BUSY);
62 else
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;
71 goto use_lock;
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;
80 use_lock:
81 return LLL_LOCK ((*lock), pshared);