> > >> + metasize = metasize > 0 ? metasize : 0; > > > > > > Why is this part needed? > > > > When an xdp_buff was initialized withouth metadata support (meta_valid > > argument of xdp_prepare_buff is false), then data_meta == data + 1. > > So this check makes sure that metadata was supported for the given xdp_buff > > and metasize is not -1 (data - data_meta). > > > > But you have a good point here: Because we have control over the > > initialization of xdp_buff in the tun_build_skb function (first code path), > > we know, that metadata is always supported for that buffer and metasize > > is never < 0. So this check is redundant and I'll remove it. > > > > But in the tun_xdp_one function (second code path), I'd prefer to keep that > > check, as the xdp_buff is externally passed to tun_sendmsg and the tun driver > > should probably not make assumptions about the metadata support of buffers > > created by other drivers (e.g. vhost_net). > > > > Thank you for taking a look, I hope things are more clear now. > > Please use min() > Err.. max.
