--- /dev/null
+#ifndef _URCU_QSBR_STATIC_H
+#define _URCU_QSBR_STATIC_H
+
+/*
+ * urcu-qsbr-static.h
+ *
+ * Userspace RCU QSBR header.
+ *
+ * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-qsbr.h for linking
+ * dynamically with the userspace rcu QSBR library.
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
+ *
+ * This 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.
+ *
+ * This 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * IBM's contributions to this file may be relicensed under LGPLv2 or later.
+ */
+
+#include <stdlib.h>
+#include <pthread.h>
+#include <assert.h>
+#include <limits.h>
+#include <syscall.h>
+#include <unistd.h>
+
+#include <urcu/compiler.h>
+#include <urcu/arch.h>
+#include <urcu/system.h>
+#include <urcu/uatomic_arch.h>
+#include <urcu/list.h>
+#include <urcu/urcu-futex.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * This code section can only be included in LGPL 2.1 compatible source code.
+ * See below for the function call wrappers which can be used in code meant to
+ * be only linked with the Userspace RCU library. This comes with a small
+ * performance degradation on the read-side due to the added function calls.
+ * This is required to permit relinking with newer versions of the library.
+ */
+
+/*
+ * If a reader is really non-cooperative and refuses to commit its
+ * rcu_reader.ctr count to memory (there is no barrier in the reader
+ * per-se), kick it after a few loops waiting for it.
+ */
+#define KICK_READER_LOOPS 10000
+
+/*
+ * Active attempts to check for reader Q.S. before calling futex().
+ */
+#define RCU_QS_ACTIVE_ATTEMPTS 100
+
+#ifdef DEBUG_RCU
+#define rcu_assert(args...) assert(args)
+#else
+#define rcu_assert(args...)
+#endif
+
+#ifdef DEBUG_YIELD
+#include <sched.h>
+#include <time.h>
+#include <pthread.h>
+#include <unistd.h>
+
+#define YIELD_READ (1 << 0)
+#define YIELD_WRITE (1 << 1)
+
+/* maximum sleep delay, in us */
+#define MAX_SLEEP 50
+
+extern unsigned int yield_active;
+extern unsigned int __thread rand_yield;
+
+static inline void debug_yield_read(void)
+{
+ if (yield_active & YIELD_READ)
+ if (rand_r(&rand_yield) & 0x1)
+ usleep(rand_r(&rand_yield) % MAX_SLEEP);
+}
+
+static inline void debug_yield_write(void)
+{
+ if (yield_active & YIELD_WRITE)
+ if (rand_r(&rand_yield) & 0x1)
+ usleep(rand_r(&rand_yield) % MAX_SLEEP);
+}
+
+static inline void debug_yield_init(void)
+{
+ rand_yield = time(NULL) ^ pthread_self();
+}
+#else
+static inline void debug_yield_read(void)
+{
+}
+
+static inline void debug_yield_write(void)
+{
+}
+
+static inline void debug_yield_init(void)
+{
+
+}
+#endif
+
+#define RCU_GP_ONLINE (1UL << 0)
+#define RCU_GP_CTR (1UL << 1)
+
+/*
+ * Global quiescent period counter with low-order bits unused.
+ * Using a int rather than a char to eliminate false register dependencies
+ * causing stalls on some architectures.
+ */
+extern unsigned long rcu_gp_ctr;
+
+struct rcu_reader {
+ /* Data used by both reader and synchronize_rcu() */
+ unsigned long ctr;
+ /* Data used for registry */
+ struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
+ pthread_t tid;
+};
+
+extern struct rcu_reader __thread rcu_reader;
+
+extern int gp_futex;
+
+/*
+ * Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
+ */
+static inline void wake_up_gp(void)
+{
+ if (unlikely(uatomic_read(&gp_futex) == -1)) {
+ uatomic_set(&gp_futex, 0);
+ futex_noasync(&gp_futex, FUTEX_WAKE, 1,
+ NULL, NULL, 0);
+ }
+}
+
+static inline int rcu_gp_ongoing(unsigned long *ctr)
+{
+ unsigned long v;
+
+ v = CMM_LOAD_SHARED(*ctr);
+ return v && (v != rcu_gp_ctr);
+}
+
+static inline void _rcu_read_lock(void)
+{
+ rcu_assert(rcu_reader.ctr);
+}
+
+static inline void _rcu_read_unlock(void)
+{
+}
+
+static inline void _rcu_quiescent_state(void)
+{
+ cmm_smp_mb();
+ _CMM_STORE_SHARED(rcu_reader.ctr, _CMM_LOAD_SHARED(rcu_gp_ctr));
+ cmm_smp_mb(); /* write rcu_reader.ctr before read futex */
+ wake_up_gp();
+ cmm_smp_mb();
+}
+
+static inline void _rcu_thread_offline(void)
+{
+ cmm_smp_mb();
+ CMM_STORE_SHARED(rcu_reader.ctr, 0);
+ cmm_smp_mb(); /* write rcu_reader.ctr before read futex */
+ wake_up_gp();
+ cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
+}
+
+static inline void _rcu_thread_online(void)
+{
+ cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
+ _CMM_STORE_SHARED(rcu_reader.ctr, CMM_LOAD_SHARED(rcu_gp_ctr));
+ cmm_smp_mb();
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _URCU_QSBR_STATIC_H */
projects / userspace-rcu.git / blobdiff