X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=urcu%2Ftls-compat.h;h=a44b88d03066a5d5a847491496fe430f820b6ef9;hb=4b832c2a390ca145635444433273e014052cb7ec;hp=192a53609fb5f6bc445f98fdd6bc26918126687e;hpb=c85e62f37e4db48038e4494c202f5a2c923262f2;p=urcu.git

diff --git a/urcu/tls-compat.h b/urcu/tls-compat.h
index 192a536..a44b88d 100644
--- a/urcu/tls-compat.h
+++ b/urcu/tls-compat.h
@@ -44,9 +44,24 @@ extern "C" {
  * 	typedef int my_int_array_type[4];
  * 	DEFINE_URCU_TLS(my_int_array_type, var_name);
  *
- * Another exmaple:
+ * Another example:
  * 	typedef void (*call_rcu_flavor)(struct rcu_head *, XXXX);
  * 	DECLARE_URCU_TLS(call_rcu_flavor, p_call_rcu);
+ *
+ * NOTE: URCU_TLS() is NOT async-signal-safe, you can't use it
+ * inside any function which can be called from signal handler.
+ *
+ * But if pthread_getspecific() is async-signal-safe in your
+ * platform, you can make URCU_TLS() async-signal-safe via:
+ * ensuring the first call to URCU_TLS() of a given TLS variable of
+ * all threads is called earliest from a non-signal handler function.
+ *
+ * Example: In any thread, the first call of URCU_TLS(rcu_reader)
+ * is called from rcu_register_thread(), so we can ensure all later
+ * URCU_TLS(rcu_reader) in any thread is async-signal-safe.
+ *
+ * Moreover, URCU_TLS variables should not be touched from signal
+ * handlers setup with with sigaltstack(2).
  */
 
 # define DECLARE_URCU_TLS(type, name)	\