Subject: Re: [PATCH v2 net-next] bridge: Fix incorrect judgment of promisc

From: "Michael S. Tsirkin" <[email-masked]>
Date: Thu, 5 Jun 2014 15:30:39 +0300

On Thu, Jun 05, 2014 at 08:53:32PM +0900, Toshiaki Makita wrote:
> br_manage_promisc() incorrectly expects br_auto_port() to return only 0
> or 1, while it actually returns flags, i.e., a subset of BR_AUTO_MASK.
> 
> Signed-off-by: Toshiaki Makita <[email-masked]>
> ---
>  net/bridge/br_if.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> index a08d2b8..3eca3fd 100644
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -153,7 +153,8 @@ void br_manage_promisc(struct net_bridge *br)
>  			 * This lets us disable promiscuous mode and write
>  			 * this config to hw.
>  			 */
> -			if (br->auto_cnt <= br_auto_port(p))
> +			if (br->auto_cnt == 0 ||
> +			    (br->auto_cnt == 1 && br_auto_port(p)))
>  				br_port_clear_promisc(p);
>  			else
>  				br_port_set_promisc(p);

It's all a nasty side-effect of using macros IMHO.

How about we just make these inline functions returning bool?

The bugfix will fall out naturally.

Signed-off-by: Michael S. Tsirkin <[email-masked]>

Warning: untested.

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 53d6e32..5818dd2 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -200,8 +200,15 @@ struct net_bridge_port
 #endif
 };
 
-#define br_auto_port(p) ((p)->flags & BR_AUTO_MASK)
-#define br_promisc_port(p) ((p)->flags & BR_PROMISC)
+static inline bool br_auto_port(struct net_bridge_port *p)
+{
+	return p->flags & BR_AUTO_MASK;
+}
+
+static inline bool br_promisc_port(struct net_bridge_port *p)
+{
+	return p->flags & BR_PROMISC;
+}
 
 #define br_port_exists(dev) (dev->priv_flags & IFF_BRIDGE_PORT)