macvlan: Fix mc_filter calculation

On Wed, Mar 29, 2023 at 08:10:26AM +0000, patchwork-bot+netdevbpf@kernel.org wrote:
>
> Here is the summary with links:
>   - [1/2] macvlan: Skip broadcast queue if multicast with single receiver
>     https://git.kernel.org/netdev/net-next/c/d45276e75e90
>   - [2/2] macvlan: Add netlink attribute for broadcast cutoff
>     https://git.kernel.org/netdev/net-next/c/954d1fa1ac93

Sorry, I made an error and posted my patches from an earlier
revision so a follow-up fix was missing:

---8<---
The bc_cutoff patch broke the calculation of mc_filter causing
some multicast packets to not make it through to the targeted
device.

Fix this by checking whether vlan is set instead of cutoff >= 0.

Also move the cutoff < 0 logic into macvlan_recompute_bc_filter
so that it doesn't change the mc_filter at all.

Fixes: d45276e7 ("macvlan: Skip broadcast queue if multicast with single receiver")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macvlan.c

@@ -792,24 +792,20 @@ static void macvlan_compute_filter(unsigned long *mc_filter,
 				   struct macvlan_dev *vlan, int cutoff)
 {
 	if (dev->flags & (IFF_PROMISC | IFF_ALLMULTI)) {
-		if (cutoff >= 0)
-			bitmap_fill(mc_filter, MACVLAN_MC_FILTER_SZ);
-		else
-			bitmap_zero(mc_filter, MACVLAN_MC_FILTER_SZ);
+		bitmap_fill(mc_filter, MACVLAN_MC_FILTER_SZ);
 	} else {
 		DECLARE_BITMAP(filter, MACVLAN_MC_FILTER_SZ);
 		struct netdev_hw_addr *ha;
 
 		bitmap_zero(filter, MACVLAN_MC_FILTER_SZ);
 		netdev_for_each_mc_addr(ha, dev) {
-			if (cutoff >= 0 && ha->synced <= cutoff)
+			if (!vlan && ha->synced <= cutoff)
 				continue;
 
 			__set_bit(mc_hash(vlan, ha->addr), filter);
 		}
 
-		if (cutoff >= 0)
-			__set_bit(mc_hash(vlan, dev->broadcast), filter);
+		__set_bit(mc_hash(vlan, dev->broadcast), filter);
 
 		bitmap_copy(mc_filter, filter, MACVLAN_MC_FILTER_SZ);
 	}
@@ -817,6 +813,11 @@ static void macvlan_compute_filter(unsigned long *mc_filter,
 
 static void macvlan_recompute_bc_filter(struct macvlan_dev *vlan)
 {
+	if (vlan->port->bc_cutoff < 0) {
+		bitmap_zero(vlan->port->bc_filter, MACVLAN_MC_FILTER_SZ);
+		return;
+	}
+
 	macvlan_compute_filter(vlan->port->bc_filter, vlan->lowerdev, NULL,
 			       vlan->port->bc_cutoff);
 }