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Diffstat (limited to 'libgomp/config/linux/lock.c')
| -rw-r--r-- | libgomp/config/linux/lock.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/libgomp/config/linux/lock.c b/libgomp/config/linux/lock.c new file mode 100644 index 00000000000..211f6007b43 --- /dev/null +++ b/libgomp/config/linux/lock.c @@ -0,0 +1,182 @@ +/* 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) |