summaryrefslogtreecommitdiff
path: root/lib/libpthread/pthread_lock.c
diff options
context:
space:
mode:
authorthorpej <thorpej@NetBSD.org>2003-01-18 10:32:11 +0000
committerthorpej <thorpej@NetBSD.org>2003-01-18 10:32:11 +0000
commitc62a74e6d5cfb2fb5034e98b983da7e2fc87709d (patch)
treef1281fd7111ddb57951e4472b342b53a2f56244a /lib/libpthread/pthread_lock.c
parentaf919042eceb8c19f42acd688efa8cf58168af5d (diff)
Merge the nathanw_sa branch.
Diffstat (limited to 'lib/libpthread/pthread_lock.c')
-rw-r--r--lib/libpthread/pthread_lock.c368
1 files changed, 368 insertions, 0 deletions
diff --git a/lib/libpthread/pthread_lock.c b/lib/libpthread/pthread_lock.c
new file mode 100644
index 00000000000..9e56c905ee7
--- /dev/null
+++ b/lib/libpthread/pthread_lock.c
@@ -0,0 +1,368 @@
+/* $NetBSD: pthread_lock.c,v 1.2 2003/01/18 10:34:15 thorpej Exp $ */
+
+/*-
+ * Copyright (c) 2001 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Nathan J. Williams.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the NetBSD
+ * Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/param.h>
+#include <sys/ras.h>
+#include <sys/sysctl.h>
+
+#include <assert.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include "pthread.h"
+#include "pthread_int.h"
+
+#undef PTHREAD_SPIN_DEBUG
+
+#ifdef PTHREAD_SPIN_DEBUG
+#define SDPRINTF(x) DPRINTF(x)
+#else
+#define SDPRINTF(x)
+#endif
+
+/* How many times to try before checking whether we've been continued. */
+#define NSPINS 1 /* no point in actually spinning until MP works */
+
+static int nspins = NSPINS;
+
+extern char pthread__lock_ras_start[], pthread__lock_ras_end[];
+
+static void
+pthread__ras_simple_lock_init(__cpu_simple_lock_t *alp)
+{
+
+ *alp = __SIMPLELOCK_UNLOCKED;
+}
+
+static int
+pthread__ras_simple_lock_try(__cpu_simple_lock_t *alp)
+{
+ __cpu_simple_lock_t old;
+
+ /* This is the atomic sequence. */
+ __asm __volatile("pthread__lock_ras_start:");
+ old = *alp;
+ *alp = __SIMPLELOCK_LOCKED;
+ __asm __volatile("pthread__lock_ras_end:");
+
+ return (old == __SIMPLELOCK_UNLOCKED);
+}
+
+static void
+pthread__ras_simple_unlock(__cpu_simple_lock_t *alp)
+{
+
+ *alp = __SIMPLELOCK_UNLOCKED;
+}
+
+static const struct pthread_lock_ops pthread__lock_ops_ras = {
+ pthread__ras_simple_lock_init,
+ pthread__ras_simple_lock_try,
+ pthread__ras_simple_unlock,
+};
+
+static void
+pthread__atomic_simple_lock_init(__cpu_simple_lock_t *alp)
+{
+
+ __cpu_simple_lock_init(alp);
+}
+
+static int
+pthread__atomic_simple_lock_try(__cpu_simple_lock_t *alp)
+{
+
+ return (__cpu_simple_lock_try(alp));
+}
+
+static void
+pthread__atomic_simple_unlock(__cpu_simple_lock_t *alp)
+{
+
+ __cpu_simple_unlock(alp);
+}
+
+static const struct pthread_lock_ops pthread__lock_ops_atomic = {
+ pthread__atomic_simple_lock_init,
+ pthread__atomic_simple_lock_try,
+ pthread__atomic_simple_unlock,
+};
+
+/*
+ * We default to pointing to the RAS primitives; we might need to use
+ * locks early, but before main() starts. This is safe, since no other
+ * threads will be active for the process, so atomicity will not be
+ * required.
+ */
+const struct pthread_lock_ops *pthread__lock_ops = &pthread__lock_ops_ras;
+
+/*
+ * Initialize the locking primitives. On uniprocessors, we always
+ * use Restartable Atomic Sequences if they are available. Otherwise,
+ * we fall back onto machine-dependent atomic lock primitives.
+ */
+void
+pthread__lockprim_init(void)
+{
+ int mib[2];
+ size_t len;
+ int ncpu;
+
+ mib[0] = CTL_HW;
+ mib[1] = HW_NCPU;
+
+ len = sizeof(ncpu);
+ sysctl(mib, 2, &ncpu, &len, NULL, 0);
+
+ if (ncpu == 1 &&
+ rasctl(pthread__lock_ras_start,
+ (caddr_t)pthread__lock_ras_end -
+ (caddr_t)pthread__lock_ras_start, RAS_INSTALL) == 0) {
+ pthread__lock_ops = &pthread__lock_ops_ras;
+ return;
+ }
+
+ pthread__lock_ops = &pthread__lock_ops_atomic;
+}
+
+void
+pthread_lockinit(pthread_spin_t *lock)
+{
+
+ pthread__simple_lock_init(lock);
+}
+
+void
+pthread_spinlock(pthread_t thread, pthread_spin_t *lock)
+{
+ int count, ret;
+
+ count = nspins;
+ SDPRINTF(("(pthread_spinlock %p) incrementing spinlock %p (count %d)\n",
+ thread, lock, thread->pt_spinlocks));
+#ifdef PTHREAD_SPIN_DEBUG
+ if(!(thread->pt_spinlocks >= 0)) {
+ (void)kill(getpid(), SIGABRT);
+ _exit(1);
+ }
+#endif
+ ++thread->pt_spinlocks;
+
+ do {
+ while (((ret = pthread__simple_lock_try(lock)) == 0) && --count)
+ ;
+
+ if (ret == 1)
+ break;
+
+ SDPRINTF(("(pthread_spinlock %p) decrementing spinlock %p (count %d)\n",
+ thread, lock, thread->pt_spinlocks));
+ --thread->pt_spinlocks;
+
+ /*
+ * We may be preempted while spinning. If so, we will
+ * be restarted here if thread->pt_spinlocks is
+ * nonzero, which can happen if:
+ * a) we just got the lock
+ * b) we haven't yet decremented the lock count.
+ * If we're at this point, (b) applies. Therefore,
+ * check if we're being continued, and if so, bail.
+ * (in case (a), we should let the code finish and
+ * we will bail out in pthread_spinunlock()).
+ */
+ if (thread->pt_next != NULL) {
+ PTHREADD_ADD(PTHREADD_SPINPREEMPT);
+ pthread__switch(thread, thread->pt_next);
+ }
+ /* try again */
+ count = nspins;
+ SDPRINTF(("(pthread_spinlock %p) incrementing spinlock from %d\n",
+ thread, thread->pt_spinlocks));
+ ++thread->pt_spinlocks;
+ } while (/*CONSTCOND*/1);
+
+ PTHREADD_ADD(PTHREADD_SPINLOCKS);
+ /* Got it! We're out of here. */
+}
+
+
+int
+pthread_spintrylock(pthread_t thread, pthread_spin_t *lock)
+{
+ int ret;
+
+ SDPRINTF(("(pthread_spinlock %p) incrementing spinlock from %d\n",
+ thread, thread->pt_spinlocks));
+ ++thread->pt_spinlocks;
+
+ ret = pthread__simple_lock_try(lock);
+
+ if (ret == 0) {
+ SDPRINTF(("(pthread_spintrylock %p) decrementing spinlock from %d\n",
+ thread, thread->pt_spinlocks));
+ --thread->pt_spinlocks;
+ /* See above. */
+ if (thread->pt_next != NULL) {
+ PTHREADD_ADD(PTHREADD_SPINPREEMPT);
+ pthread__switch(thread, thread->pt_next);
+ }
+ }
+
+ return ret;
+}
+
+
+void
+pthread_spinunlock(pthread_t thread, pthread_spin_t *lock)
+{
+
+ pthread__simple_unlock(lock);
+ SDPRINTF(("(pthread_spinunlock %p) decrementing spinlock %p (count %d)\n",
+ thread, lock, thread->pt_spinlocks));
+ --thread->pt_spinlocks;
+#ifdef PTHREAD_SPIN_DEBUG
+ if (!(thread->pt_spinlocks >= 0)) {
+ (void)kill(getpid(), SIGABRT);
+ _exit(1);
+ }
+#endif
+ PTHREADD_ADD(PTHREADD_SPINUNLOCKS);
+
+ /*
+ * If we were preempted while holding a spinlock, the
+ * scheduler will notice this and continue us. To be good
+ * citzens, we must now get out of here if that was our
+ * last spinlock.
+ * XXX when will we ever have more than one?
+ */
+
+ if ((thread->pt_spinlocks == 0) && (thread->pt_next != NULL)) {
+ PTHREADD_ADD(PTHREADD_SPINPREEMPT);
+ pthread__switch(thread, thread->pt_next);
+ }
+}
+
+
+/*
+ * Public (POSIX-specified) spinlocks.
+ * These don't interact with the spin-preemption code, nor do they
+ * perform any adaptive sleeping.
+ */
+
+int
+pthread_spin_init(pthread_spinlock_t *lock, int pshared)
+{
+
+#ifdef ERRORCHECK
+ if ((lock == NULL) ||
+ ((pshared != PTHREAD_PROCESS_PRIVATE) &&
+ (pshared != PTHREAD_PROCESS_SHARED)))
+ return EINVAL;
+#endif
+ lock->pts_magic = _PT_SPINLOCK_MAGIC;
+ /*
+ * We don't actually use the pshared flag for anything;
+ * cpu simple locks have all the process-shared properties
+ * that we want anyway.
+ */
+ lock->pts_flags = pshared;
+ pthread_lockinit(&lock->pts_spin);
+
+ return 0;
+}
+
+int
+pthread_spin_destroy(pthread_spinlock_t *lock)
+{
+
+#ifdef ERRORCHECK
+ if ((lock == NULL) || (lock->pts_magic != _PT_SPINLOCK_MAGIC))
+ return EINVAL;
+
+ if (lock->pts_spin != __SIMPLELOCK_UNLOCKED)
+ return EBUSY;
+#endif
+
+ lock->pts_magic = _PT_SPINLOCK_DEAD;
+
+ return 0;
+}
+
+int
+pthread_spin_lock(pthread_spinlock_t *lock)
+{
+
+#ifdef ERRORCHECK
+ if ((lock == NULL) || (lock->pts_magic != _PT_SPINLOCK_MAGIC))
+ return EINVAL;
+#endif
+
+ while (pthread__simple_lock_try(&lock->pts_spin) == 0)
+ /* spin */ ;
+
+ return 0;
+}
+
+int
+pthread_spin_trylock(pthread_spinlock_t *lock)
+{
+
+#ifdef ERRORCHECK
+ if ((lock == NULL) || (lock->pts_magic != _PT_SPINLOCK_MAGIC))
+ return EINVAL;
+#endif
+
+ if (pthread__simple_lock_try(&lock->pts_spin) == 0)
+ return EBUSY;
+
+ return 0;
+}
+
+int
+pthread_spin_unlock(pthread_spinlock_t *lock)
+{
+
+#ifdef ERRORCHECK
+ if ((lock == NULL) || (lock->pts_magic != _PT_SPINLOCK_MAGIC))
+ return EINVAL;
+#endif
+
+ pthread__simple_unlock(&lock->pts_spin);
+
+ return 0;
+}