diff options
Diffstat (limited to 'nptl/sysdeps/unix/sysv/linux/s390/elision-trylock.c')
| -rw-r--r-- | nptl/sysdeps/unix/sysv/linux/s390/elision-trylock.c | 94 |
1 files changed, 0 insertions, 94 deletions
diff --git a/nptl/sysdeps/unix/sysv/linux/s390/elision-trylock.c b/nptl/sysdeps/unix/sysv/linux/s390/elision-trylock.c deleted file mode 100644 index 61447d6bf4..0000000000 --- a/nptl/sysdeps/unix/sysv/linux/s390/elision-trylock.c +++ /dev/null @@ -1,94 +0,0 @@ -/* Elided pthread mutex trylock. - Copyright (C) 2014 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 - <http://www.gnu.org/licenses/>. */ - -#include <pthread.h> -#include <pthreadP.h> -#include <lowlevellock.h> -#include <htmintrin.h> -#include <elision-conf.h> - -#define aconf __elision_aconf - -/* Try to elide a futex trylock. FUTEX is the futex variable. ADAPT_COUNT is - the adaptation counter in the mutex. */ - -int -__lll_trylock_elision (int *futex, short *adapt_count) -{ - __asm__ volatile (".machinemode \"zarch_nohighgprs\"\n\t" - ".machine \"all\"" - : : : "memory"); - - /* Implement POSIX semantics by forbiding nesting elided trylocks. - Sorry. After the abort the code is re-executed - non transactional and if the lock was already locked - return an error. */ - if (__builtin_tx_nesting_depth () > 0) - { - /* Note that this abort may terminate an outermost transaction that - was created outside glibc. - This persistently aborts the current transactions to force - them to use the default lock instead of retrying transactions - until their try_tbegin is zero. - */ - __builtin_tabort (_HTM_FIRST_USER_ABORT_CODE | 1); - } - - /* Only try a transaction if it's worth it. */ - if (*adapt_count <= 0) - { - unsigned status; - - if (__builtin_expect - ((status = __builtin_tbegin ((void *)0)) == _HTM_TBEGIN_STARTED, 1)) - { - if (*futex == 0) - return 0; - /* Lock was busy. Fall back to normal locking. */ - /* Since we are in a non-nested transaction there is no need to abort, - which is expensive. */ - __builtin_tend (); - /* Note: Changing the adapt_count here might abort a transaction on a - different cpu, but that could happen anyway when the futex is - acquired, so there's no need to check the nesting depth here. */ - if (aconf.skip_lock_busy > 0) - *adapt_count = aconf.skip_lock_busy; - } - else - { - if (status != _HTM_TBEGIN_TRANSIENT) - { - /* A persistent abort (cc 1 or 3) indicates that a retry is - probably futile. Use the normal locking now and for the - next couple of calls. - Be careful to avoid writing to the lock. */ - if (aconf.skip_trylock_internal_abort > 0) - *adapt_count = aconf.skip_trylock_internal_abort; - } - } - /* Could do some retries here. */ - } - else - { - /* Lost updates are possible, but harmless. Due to races this might lead - to *adapt_count becoming less than zero. */ - (*adapt_count)--; - } - - return lll_trylock (*futex); -} |