[PATCH 3/3] sched/wait: avoid double initialization in ___wait_event()

[glider at google.com]

With CONFIG_INIT_STACK_ALL enabled, the local __wq_entry is initialized
twice. Because Clang is currently unable to optimize the automatic
initialization away (init_wait_entry() is defined in another translation
unit), remove it with the __do_not_initialize annotation.

Cc: Kees Cook <keescook at chromium.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Alexander Potapenko <glider at google.com>
---
 include/linux/wait.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 3283c8d021377..03b831ee9b64a 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -262,7 +262,8 @@ extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags);
 #define ___wait_event(wq_head, condition, state, exclusive, ret, cmd)		\
 ({										\
 	__label__ __out;							\
-	struct wait_queue_entry __wq_entry;					\
+	/* Unconditionally initialized by init_wait_entry(). */			\
+	struct wait_queue_entry __wq_entry __do_not_initialize;			\
 	long __ret = ret;	/* explicit shadow */				\
 										\
 	init_wait_entry(&__wq_entry, exclusive ? WQ_FLAG_EXCLUSIVE : 0);	\
-- 
2.25.0.265.gbab2e86ba0-goog