On 12/11/2020 02:53, Nikolay Aleksandrov wrote:
> On 11/11/2020 21:37, Pablo Neira Ayuso wrote:
>> Add .ndo_fill_forward_path for bridge devices.
>>
>> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
>> ---
>> include/linux/netdevice.h | 1 +
>> net/bridge/br_device.c | 24 ++++++++++++++++++++++++
>> 2 files changed, 25 insertions(+)
>>
>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>> index ca8525a1a797..d26de9a3d382 100644
>> --- a/include/linux/netdevice.h
>> +++ b/include/linux/netdevice.h
>> @@ -836,6 +836,7 @@ typedef u16 (*select_queue_fallback_t)(struct net_device *dev,
>> enum net_device_path_type {
>> DEV_PATH_ETHERNET = 0,
>> DEV_PATH_VLAN,
>> + DEV_PATH_BRIDGE,
>> };
>>
>> struct net_device_path {
>> diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
>> index 387403931a63..4c3a5334abe0 100644
>> --- a/net/bridge/br_device.c
>> +++ b/net/bridge/br_device.c
>> @@ -391,6 +391,29 @@ static int br_del_slave(struct net_device *dev, struct net_device *slave_dev)
>> return br_del_if(br, slave_dev);
>> }
>>
>> +static int br_fill_forward_path(struct net_device_path_ctx *ctx,
>> + struct net_device_path *path)
>> +{
>> + struct net_bridge_fdb_entry *f;
>> + struct net_bridge_port *dst;
>> + struct net_bridge *br;
>> +
>> + if (netif_is_bridge_port(ctx->dev))
>> + return -1;
>> +
>> + br = netdev_priv(ctx->dev);
>> + f = br_fdb_find_rcu(br, ctx->daddr, 0);
>> + if (!f || !f->dst)
>> + return -1;
>> +
>> + dst = READ_ONCE(f->dst);
>
> While this is ok, I meant that you have to test the ptr after. In theory between
> the !f->dst test above and now it could've become null, so to make it future-proof
> please test the null dst after deref, after the READ_ONCE(). I realize currently
> there are still problems after the change but we'll fix them.
>
On a second read this sounds too vague. :) I meant that there are still similar issues in
the bridge code today which I'll take care of. For this patch what I suggested should be enough.
Thanks,
Nik
>> + path->type = DEV_PATH_BRIDGE;
>> + path->dev = dst->br->dev;
>> + ctx->dev = dst->dev;
>> +
>> + return 0;
>> +}
>> +
>> static const struct ethtool_ops br_ethtool_ops = {
>> .get_drvinfo = br_getinfo,
>> .get_link = ethtool_op_get_link,
>> @@ -425,6 +448,7 @@ static const struct net_device_ops br_netdev_ops = {
>> .ndo_bridge_setlink = br_setlink,
>> .ndo_bridge_dellink = br_dellink,
>> .ndo_features_check = passthru_features_check,
>> + .ndo_fill_forward_path = br_fill_forward_path,
>> };
>>
>> static struct device_type br_type = {
>>
>
