X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=urcu-qsbr-static.h;h=c0467cd0e1606c87a522e56d2299716cf6402b3e;hb=6ee91d83a7a5b33160158f57f94dd75e6d0a67ed;hp=887dc3d64e949ab843a248846e4286b4fbdbf7bb;hpb=ac258107eb2e669d6f8210c86164f1b2a028f5fc;p=urcu.git

diff --git a/urcu-qsbr-static.h b/urcu-qsbr-static.h
index 887dc3d..c0467cd 100644
--- a/urcu-qsbr-static.h
+++ b/urcu-qsbr-static.h
@@ -162,7 +162,7 @@ static inline void reader_barrier()
 }
 
 #define RCU_GP_ONLINE		(1UL << 0)
-#define RCU_GP_COUNT		(1UL << 1)
+#define RCU_GP_CTR		(1UL << 1)
 
 /*
  * Global quiescent period counter with low-order bits unused.
@@ -173,6 +173,17 @@ extern unsigned long urcu_gp_ctr;
 
 extern unsigned long __thread rcu_reader_qs_gp;
 
+#if (BITS_PER_LONG < 64)
+static inline int rcu_gp_ongoing(unsigned long *value)
+{
+	unsigned long reader_gp;
+
+	if (value == NULL)
+		return 0;
+	reader_gp = LOAD_SHARED(*value);
+	return reader_gp && ((reader_gp ^ urcu_gp_ctr) & RCU_GP_CTR);
+}
+#else /* !(BITS_PER_LONG < 64) */
 static inline int rcu_gp_ongoing(unsigned long *value)
 {
 	unsigned long reader_gp;
@@ -182,6 +193,7 @@ static inline int rcu_gp_ongoing(unsigned long *value)
 	reader_gp = LOAD_SHARED(*value);
 	return reader_gp && (reader_gp - urcu_gp_ctr > ULONG_MAX / 2);
 }
+#endif  /* !(BITS_PER_LONG < 64) */
 
 static inline void _rcu_read_lock(void)
 {
@@ -232,6 +244,22 @@ static inline void _rcu_thread_online(void)
 		STORE_SHARED(p, v);			\
 	})
 
+/**
+ * _rcu_cmpxchg_pointer - same as rcu_assign_pointer, but tests if the pointer
+ * is as expected by "old". If succeeds, returns the previous pointer to the
+ * data structure, which can be safely freed after waiting for a quiescent state
+ * using synchronize_rcu(). If fails (unexpected value), returns old (which
+ * should not be freed !).
+ */
+
+#define _rcu_cmpxchg_pointer(p, old, _new)		\
+	({						\
+		if (!__builtin_constant_p(_new) ||	\
+		    ((_new) != NULL))			\
+			wmb();				\
+		cmpxchg(p, old, _new);			\
+	})
+
 /**
  * _rcu_xchg_pointer - same as rcu_assign_pointer, but returns the previous
  * pointer to the data structure, which can be safely freed after waiting for a