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authorMike Frysinger <vapier@gentoo.org>2006-01-31 05:05:15 +0000
committerMike Frysinger <vapier@gentoo.org>2006-01-31 05:05:15 +0000
commitcccc549ced940c85039c8ce263c8bb571f244afd (patch)
treeef77a870db7211ad6f511867fc56ee1a1a8b4c18 /libpthread/linuxthreads/spinlock.h
parente73b1211737842732951f9b9049294ef732e1ef0 (diff)
initial import of latest linuxthreads
Diffstat (limited to 'libpthread/linuxthreads/spinlock.h')
-rw-r--r--libpthread/linuxthreads/spinlock.h218
1 files changed, 218 insertions, 0 deletions
diff --git a/libpthread/linuxthreads/spinlock.h b/libpthread/linuxthreads/spinlock.h
new file mode 100644
index 000000000..ff96fc336
--- /dev/null
+++ b/libpthread/linuxthreads/spinlock.h
@@ -0,0 +1,218 @@
+/* Linuxthreads - a simple clone()-based implementation of Posix */
+/* threads for Linux. */
+/* Copyright (C) 1998 Xavier Leroy (Xavier.Leroy@inria.fr) */
+/* */
+/* This program is free software; you can redistribute it and/or */
+/* modify it under the terms of the GNU Library General Public License */
+/* as published by the Free Software Foundation; either version 2 */
+/* of the License, or (at your option) any later version. */
+/* */
+/* This program 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 Library General Public License for more details. */
+
+#include <bits/initspin.h>
+
+
+/* There are 2 compare and swap synchronization primitives with
+ different semantics:
+
+ 1. compare_and_swap, which has acquire semantics (i.e. it
+ completes befor subsequent writes.)
+ 2. compare_and_swap_with_release_semantics, which has release
+ semantics (it completes after previous writes.)
+
+ For those platforms on which they are the same. HAS_COMPARE_AND_SWAP
+ should be defined. For those platforms on which they are different,
+ HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS has to be defined. */
+
+#ifndef HAS_COMPARE_AND_SWAP
+#ifdef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS
+#define HAS_COMPARE_AND_SWAP
+#endif
+#endif
+
+#if defined(TEST_FOR_COMPARE_AND_SWAP)
+
+extern int __pthread_has_cas;
+extern int __pthread_compare_and_swap(long * ptr, long oldval, long newval,
+ int * spinlock);
+
+static inline int compare_and_swap(long * ptr, long oldval, long newval,
+ int * spinlock)
+{
+ if (__builtin_expect (__pthread_has_cas, 1))
+ return __compare_and_swap(ptr, oldval, newval);
+ else
+ return __pthread_compare_and_swap(ptr, oldval, newval, spinlock);
+}
+
+#elif defined(HAS_COMPARE_AND_SWAP)
+
+#ifdef IMPLEMENT_TAS_WITH_CAS
+#define testandset(p) !__compare_and_swap((long int *) p, 0, 1)
+#endif
+
+#ifdef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS
+
+static inline int
+compare_and_swap_with_release_semantics (long * ptr, long oldval,
+ long newval, int * spinlock)
+{
+ return __compare_and_swap_with_release_semantics (ptr, oldval,
+ newval);
+}
+
+#endif
+
+static inline int compare_and_swap(long * ptr, long oldval, long newval,
+ int * spinlock)
+{
+ return __compare_and_swap(ptr, oldval, newval);
+}
+
+#else
+
+extern int __pthread_compare_and_swap(long * ptr, long oldval, long newval,
+ int * spinlock);
+
+static inline int compare_and_swap(long * ptr, long oldval, long newval,
+ int * spinlock)
+{
+ return __pthread_compare_and_swap(ptr, oldval, newval, spinlock);
+}
+
+#endif
+
+#ifndef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS
+#define compare_and_swap_with_release_semantics compare_and_swap
+#define __compare_and_swap_with_release_semantics __compare_and_swap
+#endif
+
+/* Internal locks */
+
+extern void internal_function __pthread_lock(struct _pthread_fastlock * lock,
+ pthread_descr self);
+extern int __pthread_unlock(struct _pthread_fastlock *lock);
+
+static inline void __pthread_init_lock(struct _pthread_fastlock * lock)
+{
+ lock->__status = 0;
+ lock->__spinlock = __LT_SPINLOCK_INIT;
+}
+
+static inline int __pthread_trylock (struct _pthread_fastlock * lock)
+{
+#if defined TEST_FOR_COMPARE_AND_SWAP
+ if (!__pthread_has_cas)
+#endif
+#if !defined HAS_COMPARE_AND_SWAP || defined TEST_FOR_COMPARE_AND_SWAP
+ {
+ return (testandset(&lock->__spinlock) ? EBUSY : 0);
+ }
+#endif
+
+#if defined HAS_COMPARE_AND_SWAP
+ do {
+ if (lock->__status != 0) return EBUSY;
+ } while(! __compare_and_swap(&lock->__status, 0, 1));
+ return 0;
+#endif
+}
+
+/* Variation of internal lock used for pthread_mutex_t, supporting
+ timed-out waits. Warning: do not mix these operations with the above ones
+ over the same lock object! */
+
+extern void __pthread_alt_lock(struct _pthread_fastlock * lock,
+ pthread_descr self);
+
+extern int __pthread_alt_timedlock(struct _pthread_fastlock * lock,
+ pthread_descr self, const struct timespec *abstime);
+
+extern void __pthread_alt_unlock(struct _pthread_fastlock *lock);
+
+static inline void __pthread_alt_init_lock(struct _pthread_fastlock * lock)
+{
+ lock->__status = 0;
+ lock->__spinlock = __LT_SPINLOCK_INIT;
+}
+
+static inline int __pthread_alt_trylock (struct _pthread_fastlock * lock)
+{
+#if defined TEST_FOR_COMPARE_AND_SWAP
+ if (!__pthread_has_cas)
+#endif
+#if !defined HAS_COMPARE_AND_SWAP || defined TEST_FOR_COMPARE_AND_SWAP
+ {
+ int res = EBUSY;
+
+ if (testandset(&lock->__spinlock) == 0)
+ {
+ if (lock->__status == 0)
+ {
+ lock->__status = 1;
+ WRITE_MEMORY_BARRIER();
+ res = 0;
+ }
+ lock->__spinlock = __LT_SPINLOCK_INIT;
+ }
+ return res;
+ }
+#endif
+
+#if defined HAS_COMPARE_AND_SWAP
+ do {
+ if (lock->__status != 0) return EBUSY;
+ } while(! compare_and_swap(&lock->__status, 0, 1, &lock->__spinlock));
+ return 0;
+#endif
+}
+
+/* Operations on pthread_atomic, which is defined in internals.h */
+
+static inline long atomic_increment(struct pthread_atomic *pa)
+{
+ long oldval;
+
+ do {
+ oldval = pa->p_count;
+ } while (!compare_and_swap(&pa->p_count, oldval, oldval + 1, &pa->p_spinlock));
+
+ return oldval;
+}
+
+
+static inline long atomic_decrement(struct pthread_atomic *pa)
+{
+ long oldval;
+
+ do {
+ oldval = pa->p_count;
+ } while (!compare_and_swap(&pa->p_count, oldval, oldval - 1, &pa->p_spinlock));
+
+ return oldval;
+}
+
+
+static inline __attribute__((always_inline)) void
+__pthread_set_own_extricate_if (pthread_descr self, pthread_extricate_if *peif)
+{
+ /* Only store a non-null peif if the thread has cancellation enabled.
+ Otherwise pthread_cancel will unconditionally call the extricate handler,
+ and restart the thread giving rise to forbidden spurious wakeups. */
+ if (peif == NULL
+ || THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE)
+ {
+ /* If we are removing the extricate interface, we need to synchronize
+ against pthread_cancel so that it does not continue with a pointer
+ to a deallocated pthread_extricate_if struct! The thread lock
+ is (ab)used for this synchronization purpose. */
+ if (peif == NULL)
+ __pthread_lock (THREAD_GETMEM(self, p_lock), self);
+ THREAD_SETMEM(self, p_extricate, peif);
+ if (peif == NULL)
+ __pthread_unlock (THREAD_GETMEM(self, p_lock));
+ }
+}