ratelimit: fix WARN_ON_RATELIMIT return value

The macro is to be used similarly as WARN_ON as:

  if (WARN_ON_RATELIMIT(condition, state))
	do_something();

One would expect only 'condition' to affect the 'if', but
WARN_ON_RATELIMIT does internally only:

  WARN_ON((condition) && __ratelimit(state))

So the 'if' is affected by the ratelimiting state too.  Fix this by
returning 'condition' in any case.

Note that nobody uses WARN_ON_RATELIMIT yet, so there is nothing to
worry about.  But I was about to use it and was a bit surprised.

Link: http://lkml.kernel.org/r/20161215093224.23126-1-jslaby@suse.cz
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/ratelimit.h

@@ -77,8 +77,11 @@ extern int ___ratelimit(struct ratelimit_state *rs, const char *func);
 
 #ifdef CONFIG_PRINTK
 
-#define WARN_ON_RATELIMIT(condition, state)			\
-		WARN_ON((condition) && __ratelimit(state))
+#define WARN_ON_RATELIMIT(condition, state)	({		\
+	bool __rtn_cond = !!(condition);			\
+	WARN_ON(__rtn_cond && __ratelimit(state));		\
+	__rtn_cond;						\
+})
 
 #define WARN_RATELIMIT(condition, format, ...)			\
 ({								\