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;
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)
{
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