Document sigaltstack(2) limitation

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/README b/README
index 33038af3ab12c0cc96aacbedf3cf6e76ea2fd5f7..303c6ec48fc0fd948de29d1bc1319e523d7eadd4 100644 (file)
--- a/README
+++ b/README
@@ -189,11 +189,12 @@ Being careful with signals
        signal(7). The liburcu-mb and liburcu-qsbr versions of the Userspace RCU
        library do not require any signal.
 
-       Read-side critical sections are allowed in a signal handler with
-       liburcu and liburcu-mb. Be careful, however, to disable these signals
+       Read-side critical sections are allowed in a signal handler,
+       except those setup with sigaltstack(2), with liburcu and
+       liburcu-mb. Be careful, however, to disable these signals
        between thread creation and calls to rcu_register_thread(), because a
-       signal handler nesting on an unregistered thread would not be allowed to
-       call rcu_read_lock().
+       signal handler nesting on an unregistered thread would not be
+       allowed to call rcu_read_lock().
 
        Read-side critical sections are _not_ allowed in a signal handler with
        liburcu-qsbr, unless signals are disabled explicitly around each