|
Packit |
6c4009 |
/* elision-trylock.c: Lock eliding trylock for pthreads.
|
|
Packit |
6c4009 |
Copyright (C) 2015-2018 Free Software Foundation, Inc.
|
|
Packit |
6c4009 |
This file is part of the GNU C Library.
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
The GNU C Library is free software; you can redistribute it and/or
|
|
Packit |
6c4009 |
modify it under the terms of the GNU Lesser General Public
|
|
Packit |
6c4009 |
License as published by the Free Software Foundation; either
|
|
Packit |
6c4009 |
version 2.1 of the License, or (at your option) any later version.
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
The GNU C Library is distributed in the hope that it will be useful,
|
|
Packit |
6c4009 |
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
Packit |
6c4009 |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Packit |
6c4009 |
Lesser General Public License for more details.
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
You should have received a copy of the GNU Lesser General Public
|
|
Packit |
6c4009 |
License along with the GNU C Library; if not, see
|
|
Packit |
6c4009 |
<http://www.gnu.org/licenses/>. */
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
#include <pthread.h>
|
|
Packit |
6c4009 |
#include <pthreadP.h>
|
|
Packit |
6c4009 |
#include <lowlevellock.h>
|
|
Packit |
6c4009 |
#include <elision-conf.h>
|
|
Packit |
6c4009 |
#include "htm.h"
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
#define aconf __elision_aconf
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
/* Try to elide a futex trylock. FUTEX is the futex variable. ADAPT_COUNT is
|
|
Packit |
6c4009 |
the adaptation counter in the mutex. */
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
int
|
|
Packit |
6c4009 |
__lll_trylock_elision (int *futex, short *adapt_count)
|
|
Packit |
6c4009 |
{
|
|
Packit |
6c4009 |
#ifndef __SPE__
|
|
Packit |
6c4009 |
/* Implement POSIX semantics by forbiding nesting elided trylocks. */
|
|
Packit |
6c4009 |
__libc_tabort (_ABORT_NESTED_TRYLOCK);
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
/* Only try a transaction if it's worth it. */
|
|
Packit |
6c4009 |
if (atomic_load_relaxed (adapt_count) > 0)
|
|
Packit |
6c4009 |
{
|
|
Packit |
6c4009 |
goto use_lock;
|
|
Packit |
6c4009 |
}
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
if (__libc_tbegin (0))
|
|
Packit |
6c4009 |
{
|
|
Packit |
6c4009 |
if (*futex == 0)
|
|
Packit |
6c4009 |
return 0;
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
/* Lock was busy. This is never a nested transaction.
|
|
Packit |
6c4009 |
End it, and set the adapt count. */
|
|
Packit |
6c4009 |
__libc_tend (0);
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
if (aconf.skip_lock_busy > 0)
|
|
Packit |
6c4009 |
atomic_store_relaxed (adapt_count, aconf.skip_lock_busy);
|
|
Packit |
6c4009 |
}
|
|
Packit |
6c4009 |
else
|
|
Packit |
6c4009 |
{
|
|
Packit |
6c4009 |
if (_TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
|
|
Packit |
6c4009 |
{
|
|
Packit |
6c4009 |
/* A persistent failure indicates that a retry will probably
|
|
Packit |
6c4009 |
result in another failure. Use normal locking now and
|
|
Packit |
6c4009 |
for the next couple of calls. */
|
|
Packit |
6c4009 |
if (aconf.skip_trylock_internal_abort > 0)
|
|
Packit |
6c4009 |
atomic_store_relaxed (adapt_count,
|
|
Packit |
6c4009 |
aconf.skip_trylock_internal_abort);
|
|
Packit |
6c4009 |
}
|
|
Packit |
6c4009 |
}
|
|
Packit |
6c4009 |
|
|
Packit |
6c4009 |
use_lock:
|
|
Packit |
6c4009 |
#endif
|
|
Packit |
6c4009 |
return lll_trylock (*futex);
|
|
Packit |
6c4009 |
}
|