X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=urcu.h;h=27695d495aeeb6388b121a099183949cbbdbac06;hb=e462817ecdce42b00f0cb0825e2425b08943105b;hp=b6b5c7b039e359225d947afb91a29a2f25ba6a3c;hpb=c265818b951224bcde407b1efa14f9daf44949b3;p=urcu.git

diff --git a/urcu.h b/urcu.h
index b6b5c7b..27695d4 100644
--- a/urcu.h
+++ b/urcu.h
@@ -17,6 +17,8 @@
  * Distributed under GPLv2
  */
 
+#include <stdlib.h>
+
 /* The "volatile" is due to gcc bugs */
 #define barrier() __asm__ __volatile__("": : :"memory")
 
@@ -66,41 +68,130 @@ static inline void atomic_inc(int *v)
 
 #define SIGURCU SIGUSR1
 
-/* Global quiescent period parity */
-extern int urcu_qparity;
+#ifdef DEBUG_YIELD
+#include <sched.h>
+
+#define YIELD_READ 	(1 << 0)
+#define YIELD_WRITE	(1 << 1)
+
+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)
+			sched_yield();
+}
 
-extern int __thread urcu_active_readers[2];
+static inline void debug_yield_write(void)
+{
+	if (yield_active & YIELD_WRITE)
+		if (rand_r(&rand_yield) & 0x1)
+			sched_yield();
+}
 
-static inline int get_urcu_qparity(void)
+static inline void debug_yield_init(void)
 {
-	return urcu_qparity;
+	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
 
 /*
- * urcu_parity should be declared on the caller's stack.
+ * Limiting the nesting level to 256 to keep instructions small in the read
+ * fast-path.
  */
-static inline void rcu_read_lock(int *urcu_parity)
+#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 int __thread urcu_active_readers;
+
+static inline int rcu_old_gp_ongoing(int *value)
+{
+	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)
 {
-	*urcu_parity = get_urcu_qparity();
-	urcu_active_readers[*urcu_parity]++;
+	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(int *urcu_parity)
+static inline void rcu_read_unlock(void)
 {
+	debug_yield_read();
 	barrier();
+	debug_yield_read();
 	/*
 	 * Finish using rcu before decrementing the pointer.
 	 * See force_mb_all_threads().
 	 */
-	urcu_active_readers[*urcu_parity]--;
+	urcu_active_readers -= RCU_GP_COUNT;
+	debug_yield_read();
 }
 
+/**
+ * rcu_assign_pointer - assign (publicize) a pointer to a newly
+ * initialized structure that will be dereferenced by RCU read-side
+ * critical sections.  Returns the value assigned.
+ *
+ * Inserts memory barriers on architectures that require them
+ * (pretty much all of them other than x86), and also prevents
+ * the compiler from reordering the code that initializes the
+ * structure after the pointer assignment.  More importantly, this
+ * call documents which pointers will be dereferenced by RCU read-side
+ * code.
+ */
+
+#define rcu_assign_pointer(p, v) \
+	({ \
+		if (!__builtin_constant_p(v) || \
+		    ((v) != NULL)) \
+			wmb(); \
+		(p) = (v); \
+	})
+
 extern void *urcu_publish_content(void **ptr, void *new);
+extern void synchronize_rcu(void);
 
 /*
  * Reader thread registration.