diff --git a/include/linux/signal.h b/include/linux/signal.h
index a822300..7987ce74 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -254,6 +254,7 @@
 extern int show_unhandled_signals;
 
 extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie);
+extern void block_sigmask(struct k_sigaction *ka, int signr);
 extern void exit_signals(struct task_struct *tsk);
 
 extern struct kmem_cache *sighand_cachep;