rndis_wlan: correct multicast_list handling V3

My previous patch (655ffee284dfcf9a24ac0343f3e5ee6db85b85c5) added locking in
a bad way. Because rndis_set_oid can sleep, there is need to prepare multicast
addresses into local buffer under netif_addr_lock first, then call
rndis_set_oid outside. This caused reorganizing of the whole function.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Reported-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/wireless/rndis_wlan.c b/drivers/net/wireless/rndis_wlan.c
index 9f6d6bf06b8e595eda66c13470846ade5a976e89..2887047069f217824c9d21cec142167ae1f42fbc 100644 (file)
--- a/drivers/net/wireless/rndis_wlan.c
+++ b/drivers/net/wireless/rndis_wlan.c
@@ -1496,51 +1496,67 @@ static void set_multicast_list(struct usbnet *usbdev)
 {
        struct rndis_wlan_private *priv = get_rndis_wlan_priv(usbdev);
        struct dev_mc_list *mclist;
-       __le32 filter;
-       int ret, i, size;
-       char *buf;
+       __le32 filter, basefilter;
+       int ret;
+       char *mc_addrs = NULL;
+       int mc_count;
 
-       filter = RNDIS_PACKET_TYPE_DIRECTED | RNDIS_PACKET_TYPE_BROADCAST;
+       basefilter = filter = RNDIS_PACKET_TYPE_DIRECTED |
+                             RNDIS_PACKET_TYPE_BROADCAST;
 
-       netif_addr_lock_bh(usbdev->net);
        if (usbdev->net->flags & IFF_PROMISC) {
                filter |= RNDIS_PACKET_TYPE_PROMISCUOUS |
                        RNDIS_PACKET_TYPE_ALL_LOCAL;
-       } else if (usbdev->net->flags & IFF_ALLMULTI ||
-                  netdev_mc_count(usbdev->net) > priv->multicast_size) {
+       } else if (usbdev->net->flags & IFF_ALLMULTI) {
+               filter |= RNDIS_PACKET_TYPE_ALL_MULTICAST;
+       }
+
+       if (filter != basefilter)
+               goto set_filter;
+
+       /*
+        * mc_list should be accessed holding the lock, so copy addresses to
+        * local buffer first.
+        */
+       netif_addr_lock_bh(usbdev->net);
+       mc_count = netdev_mc_count(usbdev->net);
+       if (mc_count > priv->multicast_size) {
                filter |= RNDIS_PACKET_TYPE_ALL_MULTICAST;
-       } else if (!netdev_mc_empty(usbdev->net)) {
-               size = min(priv->multicast_size, netdev_mc_count(usbdev->net));
-               buf = kmalloc(size * ETH_ALEN, GFP_KERNEL);
-               if (!buf) {
+       } else if (mc_count) {
+               int i = 0;
+
+               mc_addrs = kmalloc(mc_count * ETH_ALEN, GFP_ATOMIC);
+               if (!mc_addrs) {
                        netdev_warn(usbdev->net,
                                    "couldn't alloc %d bytes of memory\n",
-                                   size * ETH_ALEN);
+                                   mc_count * ETH_ALEN);
                        netif_addr_unlock_bh(usbdev->net);
                        return;
                }
 
-               i = 0;
-               netdev_for_each_mc_addr(mclist, usbdev->net) {
-                       if (i == size)
-                               break;
-                       memcpy(buf + i++ * ETH_ALEN, mclist->dmi_addr, ETH_ALEN);
-               }
+               netdev_for_each_mc_addr(mclist, usbdev->net)
+                       memcpy(mc_addrs + i++ * ETH_ALEN,
+                              mclist->dmi_addr, ETH_ALEN);
+       }
+       netif_addr_unlock_bh(usbdev->net);
 
-               ret = rndis_set_oid(usbdev, OID_802_3_MULTICAST_LIST, buf,
-                                                               i * ETH_ALEN);
-               if (ret == 0 && i > 0)
+       if (filter != basefilter)
+               goto set_filter;
+
+       if (mc_count) {
+               ret = rndis_set_oid(usbdev, OID_802_3_MULTICAST_LIST, mc_addrs,
+                                   mc_count * ETH_ALEN);
+               kfree(mc_addrs);
+               if (ret == 0)
                        filter |= RNDIS_PACKET_TYPE_MULTICAST;
                else
                        filter |= RNDIS_PACKET_TYPE_ALL_MULTICAST;
 
                netdev_dbg(usbdev->net, "OID_802_3_MULTICAST_LIST(%d, max: %d) -> %d\n",
-                          i, priv->multicast_size, ret);
-
-               kfree(buf);
+                          mc_count, priv->multicast_size, ret);
        }
-       netif_addr_unlock_bh(usbdev->net);
 
+set_filter:
        ret = rndis_set_oid(usbdev, OID_GEN_CURRENT_PACKET_FILTER, &filter,
                                                        sizeof(filter));
        if (ret < 0) {