batman-adv: Fix possible side-effects in _batadv_dbg

An argument of a macro should not be evaluated multiple times. Otherwise
embedded operations in these arguments will be executed multiple times.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

diff --git a/net/batman-adv/log.h b/net/batman-adv/log.h
index 7a2b9f4..65ce97e 100644 (file)
--- a/net/batman-adv/log.h
+++ b/net/batman-adv/log.h
@@ -73,9 +73,10 @@ __printf(2, 3);
 /* possibly ratelimited debug output */
 #define _batadv_dbg(type, bat_priv, ratelimited, fmt, arg...)          \
        do {                                                            \
-               if (atomic_read(&(bat_priv)->log_level) & (type) &&     \
+               struct batadv_priv *__batpriv = (bat_priv);             \
+               if (atomic_read(&__batpriv->log_level) & (type) &&      \
                    (!(ratelimited) || net_ratelimit()))                \
-                       batadv_debug_log(bat_priv, fmt, ## arg);        \
+                       batadv_debug_log(__batpriv, fmt, ## arg);       \
        }                                                               \
        while (0)
 #else /* !CONFIG_BATMAN_ADV_DEBUG */