| /* Copyright (C) 2005 Free Software Foundation, Inc. |
| Contributed by Richard Henderson <rth@redhat.com>. |
| |
| This file is part of the GNU OpenMP Library (libgomp). |
| |
| Libgomp 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. |
| |
| Libgomp 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 libgomp; see the file COPYING.LIB. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, |
| MA 02110-1301, USA. */ |
| |
| /* As a special exception, if you link this library with other files, some |
| of which are compiled with GCC, to produce an executable, this library |
| does not by itself cause the resulting executable to be covered by the |
| GNU General Public License. This exception does not however invalidate |
| any other reasons why the executable file might be covered by the GNU |
| General Public License. */ |
| |
| /* This is a Linux specific implementation of the public OpenMP locking |
| primitives. This implementation uses atomic instructions and the futex |
| syscall. */ |
| |
| #include "libgomp.h" |
| #include <string.h> |
| #include <unistd.h> |
| #include <sys/syscall.h> |
| #include "futex.h" |
| |
| |
| /* The internal gomp_mutex_t and the external non-recursive omp_lock_t |
| have the same form. Re-use it. */ |
| |
| void |
| omp_init_lock (omp_lock_t *lock) |
| { |
| gomp_mutex_init (lock); |
| } |
| |
| void |
| omp_destroy_lock (omp_lock_t *lock) |
| { |
| gomp_mutex_destroy (lock); |
| } |
| |
| void |
| omp_set_lock (omp_lock_t *lock) |
| { |
| gomp_mutex_lock (lock); |
| } |
| |
| void |
| omp_unset_lock (omp_lock_t *lock) |
| { |
| gomp_mutex_unlock (lock); |
| } |
| |
| int |
| omp_test_lock (omp_lock_t *lock) |
| { |
| return __sync_bool_compare_and_swap (lock, 0, 1); |
| } |
| |
| /* The external recursive omp_nest_lock_t form requires additional work. */ |
| |
| /* We need an integer to uniquely identify this thread. Most generally |
| this is the thread's TID, which ideally we'd get this straight from |
| the TLS block where glibc keeps it. Unfortunately, we can't get at |
| that directly. |
| |
| If we don't support (or have disabled) TLS, one function call is as |
| good (or bad) as any other. Use the syscall all the time. |
| |
| On an ILP32 system (defined here as not LP64), we can make do with |
| any thread-local pointer. Ideally we'd use the TLS base address, |
| since that requires the least amount of arithmetic, but that's not |
| always available directly. Make do with the gomp_thread pointer |
| since it's handy. */ |
| |
| #if !defined (HAVE_TLS) |
| static inline int gomp_tid (void) |
| { |
| return syscall (SYS_gettid); |
| } |
| #elif !defined(__LP64__) |
| static inline int gomp_tid (void) |
| { |
| return (int) gomp_thread (); |
| } |
| #else |
| static __thread int tid_cache; |
| static inline int gomp_tid (void) |
| { |
| int tid = tid_cache; |
| if (__builtin_expect (tid == 0, 0)) |
| tid_cache = tid = syscall (SYS_gettid); |
| return tid; |
| } |
| #endif |
| |
| |
| void |
| omp_init_nest_lock (omp_nest_lock_t *lock) |
| { |
| memset (lock, 0, sizeof (lock)); |
| } |
| |
| void |
| omp_destroy_nest_lock (omp_nest_lock_t *lock) |
| { |
| } |
| |
| void |
| omp_set_nest_lock (omp_nest_lock_t *lock) |
| { |
| int otid, tid = gomp_tid (); |
| |
| while (1) |
| { |
| otid = __sync_val_compare_and_swap (&lock->owner, 0, tid); |
| if (otid == 0) |
| { |
| lock->count = 1; |
| return; |
| } |
| if (otid == tid) |
| { |
| lock->count++; |
| return; |
| } |
| |
| futex_wait (&lock->owner, otid); |
| } |
| } |
| |
| void |
| omp_unset_nest_lock (omp_nest_lock_t *lock) |
| { |
| /* ??? Validate that we own the lock here. */ |
| |
| if (--lock->count == 0) |
| { |
| __sync_lock_release (&lock->owner); |
| futex_wake (&lock->owner, 1); |
| } |
| } |
| |
| int |
| omp_test_nest_lock (omp_nest_lock_t *lock) |
| { |
| int otid, tid = gomp_tid (); |
| |
| otid = __sync_val_compare_and_swap (&lock->owner, 0, tid); |
| if (otid == 0) |
| { |
| lock->count = 1; |
| return 1; |
| } |
| if (otid == tid) |
| return ++lock->count; |
| |
| return 0; |
| } |
| |
| ialias (omp_init_lock) |
| ialias (omp_init_nest_lock) |
| ialias (omp_destroy_lock) |
| ialias (omp_destroy_nest_lock) |
| ialias (omp_set_lock) |
| ialias (omp_set_nest_lock) |
| ialias (omp_unset_lock) |
| ialias (omp_unset_nest_lock) |
| ialias (omp_test_lock) |
| ialias (omp_test_nest_lock) |