*
* Userspace RCU header
*
- * Copyright February 2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
*
- * Credits for Paul e. McKenney <paulmck@linux.vnet.ibm.com>
- * for inspiration coming from the Linux kernel RCU and rcu-preempt.
+ * LGPL-compatible code should include this header with :
*
- * The barrier, mb, rmb, wmb, atomic_inc, smp_read_barrier_depends, ACCESS_ONCE
- * and rcu_dereference primitives come from the Linux kernel.
+ * #define _LGPL_SOURCE
+ * #include <urcu.h>
*
- * Distributed under GPLv2
+ * 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>
-/* The "volatile" is due to gcc bugs */
-#define barrier() __asm__ __volatile__("": : :"memory")
-
-/* x86 32/64 specific */
-#define mb() asm volatile("mfence":::"memory")
-#define rmb() asm volatile("lfence":::"memory")
-#define wmb() asm volatile("sfence" ::: "memory")
+/*
+ * See urcu-pointer.h and urcu/static/urcu-pointer.h for pointer
+ * publication headers.
+ */
+#include <urcu-pointer.h>
-static inline void atomic_inc(int *v)
-{
- asm volatile("lock; incl %0"
- : "+m" (*v));
-}
+#ifdef __cplusplus
+extern "C" {
+#endif
-/* Nop everywhere except on alpha. */
-#define smp_read_barrier_depends()
+#include <urcu/map/urcu.h>
/*
- * Prevent the compiler from merging or refetching accesses. The compiler
- * is also forbidden from reordering successive instances of ACCESS_ONCE(),
- * but only when the compiler is aware of some particular ordering. One way
- * to make the compiler aware of ordering is to put the two invocations of
- * ACCESS_ONCE() in different C statements.
- *
- * This macro does absolutely -nothing- to prevent the CPU from reordering,
- * merging, or refetching absolutely anything at any time. Its main intended
- * use is to mediate communication between process-level code and irq/NMI
- * handlers, all running on the same CPU.
- */
-#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
-
-/**
- * rcu_dereference - fetch an RCU-protected pointer in an
- * RCU read-side critical section. This pointer may later
- * be safely dereferenced.
+ * Important !
*
- * Inserts memory barriers on architectures that require them
- * (currently only the Alpha), and, more importantly, documents
- * exactly which pointers are protected by RCU.
+ * Each thread containing read-side critical sections must be registered
+ * with rcu_register_thread_mb() before calling rcu_read_lock_mb().
+ * rcu_unregister_thread_mb() should be called before the thread exits.
*/
-#define rcu_dereference(p) ({ \
- typeof(p) _________p1 = ACCESS_ONCE(p); \
- smp_read_barrier_depends(); \
- (_________p1); \
- })
-
-#define SIGURCU SIGUSR1
+#ifdef _LGPL_SOURCE
-#ifdef DEBUG_YIELD
-#include <sched.h>
+#include <urcu/static/urcu.h>
-#define YIELD_READ (1 << 0)
-#define YIELD_WRITE (1 << 1)
-
-extern unsigned int yield_active;
-extern unsigned int __thread rand_yield;
+/*
+ * Mappings for static use of the userspace RCU library.
+ * Should only be used in LGPL-compatible code.
+ */
-static inline void debug_yield_read(void)
-{
- if (yield_active & YIELD_READ)
- if (rand_r(&rand_yield) & 0x1)
- sched_yield();
-}
+/*
+ * rcu_read_lock()
+ * rcu_read_unlock()
+ *
+ * Mark the beginning and end of a read-side critical section.
+ * DON'T FORGET TO USE RCU_REGISTER/UNREGISTER_THREAD() FOR EACH THREAD WITH
+ * READ-SIDE CRITICAL SECTION.
+ */
+#ifdef RCU_MEMBARRIER
+#define rcu_read_lock_memb _rcu_read_lock
+#define rcu_read_unlock_memb _rcu_read_unlock
+#define rcu_read_ongoing_memb _rcu_read_ongoing
+#elif defined(RCU_SIGNAL)
+#define rcu_read_lock_sig _rcu_read_lock
+#define rcu_read_unlock_sig _rcu_read_unlock
+#define rcu_read_ongoing_sig _rcu_read_ongoing
+#elif defined(RCU_MB)
+#define rcu_read_lock_mb _rcu_read_lock
+#define rcu_read_unlock_mb _rcu_read_unlock
+#define rcu_read_ongoing_mb _rcu_read_ongoing
+#endif
-static inline void debug_yield_write(void)
-{
- if (yield_active & YIELD_WRITE)
- if (rand_r(&rand_yield) & 0x1)
- sched_yield();
-}
+#else /* !_LGPL_SOURCE */
-static inline void debug_yield_init(void)
-{
- rand_yield = time(NULL) ^ pthread_self();
-}
-#else
-static inline void debug_yield_read(void)
-{
-}
+/*
+ * library wrappers to be used by non-LGPL compatible source code.
+ * See LGPL-only urcu/static/urcu-pointer.h for documentation.
+ */
-static inline void debug_yield_write(void)
-{
-}
+extern void rcu_read_lock(void);
+extern void rcu_read_unlock(void);
+extern int rcu_read_ongoing(void);
-static inline void debug_yield_init(void)
-{
+#endif /* !_LGPL_SOURCE */
-}
-#endif
+extern void synchronize_rcu(void);
/*
- * Limiting the nesting level to 256 to keep instructions small in the read
- * fast-path.
+ * Reader thread registration.
*/
-#define RCU_GP_COUNT (1U << 0)
-#define RCU_GP_CTR_BIT (1U << 8)
-#define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_BIT - 1)
-
-/* Global quiescent period counter with low-order bits unused. */
-extern int urcu_gp_ctr;
+extern void rcu_register_thread(void);
+extern void rcu_unregister_thread(void);
-extern int __thread urcu_active_readers;
+/*
+ * Explicit rcu initialization, for "early" use within library constructors.
+ */
+extern void rcu_init(void);
-static inline int rcu_old_gp_ongoing(int *value)
+/*
+ * Q.S. reporting are no-ops for these URCU flavors.
+ */
+static inline void rcu_quiescent_state(void)
{
- int v;
-
- if (value == NULL)
- return 0;
- debug_yield_write();
- v = ACCESS_ONCE(*value);
- debug_yield_write();
- return (v & RCU_GP_CTR_NEST_MASK) &&
- ((v ^ ACCESS_ONCE(urcu_gp_ctr)) & RCU_GP_CTR_BIT);
}
-static inline void rcu_read_lock(void)
+static inline void rcu_thread_offline(void)
{
- int tmp;
-
- debug_yield_read();
- tmp = urcu_active_readers;
- debug_yield_read();
- if (!(tmp & RCU_GP_CTR_NEST_MASK))
- urcu_active_readers = urcu_gp_ctr + RCU_GP_COUNT;
- else
- urcu_active_readers = tmp + RCU_GP_COUNT;
- debug_yield_read();
- /*
- * Increment active readers count before accessing the pointer.
- * See force_mb_all_threads().
- */
- barrier();
- debug_yield_read();
}
-static inline void rcu_read_unlock(void)
+static inline void rcu_thread_online(void)
{
- debug_yield_read();
- barrier();
- debug_yield_read();
- /*
- * Finish using rcu before decrementing the pointer.
- * See force_mb_all_threads().
- */
- urcu_active_readers -= RCU_GP_COUNT;
- debug_yield_read();
}
-extern void *urcu_publish_content(void **ptr, void *new);
+#ifdef __cplusplus
+}
+#endif
-/*
- * Reader thread registration.
- */
-extern void urcu_register_thread(void);
-extern void urcu_unregister_thread(void);
+#include <urcu-call-rcu.h>
+#include <urcu-defer.h>
+#include <urcu-flavor.h>
#endif /* _URCU_H */
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