[PATCH -next] static-keys: Better error checking for static_key_enable/disable

[Chuck Ebbert <cebbert.lkml@gmail.com>]

The  warnings for static_key_enable/disable don't catch common
errors. For example, starting with a default enabled key and
calling enable doesn't cause a warning until the next enable
or disable. Check explicitly for zero or one instead of allowing
both values in every case. Generated code should be smaller too.

Signed-off-by: Chuck Ebbert <cebbert.lkml@gmail.com>

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 7f653e8..ba9ca0c 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -225,7 +225,7 @@ static inline void static_key_enable(struct static_key *key)
 {
 	int count = static_key_count(key);
 
-	WARN_ON_ONCE(count < 0 || count > 1);
+	WARN_ON_ONCE(count);
 
 	if (!count)
 		static_key_slow_inc(key);
@@ -235,7 +235,7 @@ static inline void static_key_disable(struct static_key *key)
 {
 	int count = static_key_count(key);
 
-	WARN_ON_ONCE(count < 0 || count > 1);
+	WARN_ON_ONCE(count != 1);
 
 	if (count)
 		static_key_slow_dec(key);