*
* Copyright February 2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
*
- * Credits for Paul e. McKenney <paulmck@linux.vnet.ibm.com>
+ * Credits for Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* for inspiration coming from the Linux kernel RCU and rcu-preempt.
*
- * The barrier, mb, rmb, wmb, atomic_inc, smp_read_barrier_depends, ACCESS_ONCE
- * and rcu_dereference primitives come from the Linux kernel.
+ * LGPL-compatible code should include this header with :
*
- * Distributed under GPLv2
+ * #define _LGPL_SOURCE
+ * #include <urcu.h>
+ *
+ * Distributed under LGPLv2.1
+ *
+ * IBM's contributions to this file may be relicensed under LGPLv2 or later.
*/
-/* The "volatile" is due to gcc bugs */
-#define barrier() __asm__ __volatile__("": : :"memory")
+#include <stdlib.h>
+#include <pthread.h>
-/* x86 32/64 specific */
-#define mb() asm volatile("mfence":::"memory")
-#define rmb() asm volatile("lfence":::"memory")
-#define wmb() asm volatile("sfence" ::: "memory")
+#ifdef _LGPL_SOURCE
-static inline void atomic_inc(int *v)
-{
- asm volatile("lock; incl %0"
- : "+m" (*v));
-}
-
-/* Nop everywhere except on alpha. */
-#define smp_read_barrier_depends()
+#include <urcu-static.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.
+ * Mappings for static use of the userspace RCU library.
+ * Should only be used in LGPL-compatible code.
*/
-#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.
- *
- * Inserts memory barriers on architectures that require them
- * (currently only the Alpha), and, more importantly, documents
- * exactly which pointers are protected by RCU.
+#define rcu_dereference _rcu_dereference
+#define rcu_read_lock _rcu_read_lock
+#define rcu_read_unlock _rcu_read_unlock
+
+#define rcu_assign_pointer _rcu_assign_pointer
+#define rcu_xchg_pointer _rcu_xchg_pointer
+#define rcu_publish_content _rcu_publish_content
+
+#else /* !_LGPL_SOURCE */
+
+/*
+ * library wrappers to be used by non-LGPL compatible source code.
*/
-#define rcu_dereference(p) ({ \
- typeof(p) _________p1 = ACCESS_ONCE(p); \
- smp_read_barrier_depends(); \
- (_________p1); \
- })
+extern void rcu_read_lock(void);
+extern void rcu_read_unlock(void);
-#define SIGURCU SIGUSR1
+extern void *rcu_dereference(void *p);
-/* Global quiescent period parity */
-extern int urcu_qparity;
+extern void *rcu_assign_pointer_sym(void **p, void *v);
-extern int __thread urcu_active_readers[2];
+#define rcu_assign_pointer(p, v) \
+ rcu_assign_pointer_sym((void **)(p), (v))
-static inline int get_urcu_qparity(void)
-{
- return urcu_qparity;
-}
+extern void *rcu_xchg_pointer_sym(void **p, void *v);
+#define rcu_xchg_pointer(p, v) \
+ rcu_xchg_pointer_sym((void **)(p), (v))
-/*
- * returns urcu_parity.
- */
-static inline int rcu_read_lock(void)
-{
- int urcu_parity = get_urcu_qparity();
- urcu_active_readers[urcu_parity]++;
- /*
- * Increment active readers count before accessing the pointer.
- * See force_mb_all_threads().
- */
- barrier();
- return urcu_parity;
-}
-
-static inline void rcu_read_unlock(int urcu_parity)
-{
- barrier();
- /*
- * Finish using rcu before decrementing the pointer.
- * See force_mb_all_threads().
- */
- urcu_active_readers[urcu_parity]--;
-}
-
-extern void rcu_write_lock(void);
-extern void rcu_write_unlock(void);
-
-extern void *_urcu_publish_content(void **ptr, void *new);
+extern void *rcu_publish_content_sym(void **p, void *v);
+#define rcu_publish_content(p, v) \
+ rcu_publish_content_sym((void **)(p), (v))
-/*
- * gcc does not like automatic &struct ... * -> void **.
- * Remove the warning. (hopefully this is ok)
- */
-#define urcu_publish_content(ptr, new) _urcu_publish_content((void **)ptr, new)
+#endif /* !_LGPL_SOURCE */
+
+extern void synchronize_rcu(void);
/*
* Reader thread registration.
*/
-extern void urcu_register_thread(void);
-extern void urcu_unregister_thread(void);
+extern void rcu_register_thread(void);
+extern void rcu_unregister_thread(void);
#endif /* _URCU_H */