Jesper Dangaard Brouer
2019-Feb-07 07:48 UTC
Resource management for ndo_xdp_xmit (Was: [PATCH net] virtio_net: Account for tx bytes and packets on sending xdp_frames)
On Wed, 6 Feb 2019 00:06:33 +0000 Saeed Mahameed <saeedm at mellanox.com> wrote:> On Mon, 2019-02-04 at 19:13 -0800, David Ahern wrote:[...]> > > > mlx5 needs some work. As I recall it still has the bug/panic > > removing xdp programs - at least I don't recall seeing a patch for > > it. > > Only when xdp_redirect to mlx5, and removing the program while > redirect is happening, this is actually due to a lack of > synchronization means between different drivers, we have some ideas > to overcome this using a standard XDP API, or just use a hack in mlx5 > driver which i don't like: > > https://git.kernel.org/pub/scm/linux/kernel/git/saeed/linux.git/commit/?h=topic/xdp-redirect-fix&id=a3652d03cc35fd3ad62744986c8ccaca74c9f20c > > I will be working on this towards the end of this week.Toke and I have been discussing how to solve this. The main idea for fixing this is to tie resource allocation to interface insertion into interface maps (kernel/bpf/devmap.c). As the =devmapalready have the needed synchronisation mechanisms and steps for safely adding and removing =net_devices= (e.g. stopping RX side, flushing remaining frames, waiting RCU period before freeing objects, etc.) As described here: https://github.com/xdp-project/xdp-project/blob/master/xdp-project.org#better-ndo_xdp_xmit-resource-management --Jesper