urcu: add hint to DEFINE_URCU_TLS() for compound types

Just a hint.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/urcu/tls-compat.h b/urcu/tls-compat.h
index 9686ecaab139343547151e0f95697324c0442a55..192a53609fb5f6bc445f98fdd6bc26918126687e 100644 (file)
--- a/urcu/tls-compat.h
+++ b/urcu/tls-compat.h
@@ -34,6 +34,21 @@ extern "C" {
 
 #ifdef CONFIG_RCU_TLS  /* Based on ax_tls.m4 */
 
+/*
+ * Hint: How to define/declare TLS variables of compound types
+ *       such as array or function pointers?
+ *
+ * Answer: Use typedef to assign a type_name to the compound type.
+ * Example: Define a TLS variable which is an int array with len=4:
+ *
+ *     typedef int my_int_array_type[4];
+ *     DEFINE_URCU_TLS(my_int_array_type, var_name);
+ *
+ * Another exmaple:
+ *     typedef void (*call_rcu_flavor)(struct rcu_head *, XXXX);
+ *     DECLARE_URCU_TLS(call_rcu_flavor, p_call_rcu);
+ */
+
 # define DECLARE_URCU_TLS(type, name)  \
        CONFIG_RCU_TLS type name