Re: Resource management for ndo_xdp_xmit (Was: [PATCH net] virtio_net: Account for tx bytes and packets on sending xdp_frames)
On Sat, 9 Feb 2019 00:18:31 +, Saeed Mahameed wrote: > On Fri, 2019-02-08 at 15:17 -0800, Saeed Mahameed wrote: > > On Thu, 2019-02-07 at 19:08 +, Saeed Mahameed wrote: > > > > > > So > > > 1) on dev_map_update_elem() we will call > > > dev->dev->ndo_bpf() to notify the device on the intention to > > > start/stop > > > redirect, and wait for it to create/destroy the HW resources > > > before/after actually updating the map > > > > > > > silly me, dev_map_update_elem must be atomic, we can't hook driver > > resource allocation to it, it must come as a separate request > > (syscall) > > from user space to request to create XDP redirect resources. > > > > Well, it is possible to render dev_map_update_elem non-atomic and fail > BPF programs who try to update it in the verifier > check_map_func_compatibility. > > if you know of any case where devmap needs to be updated from the BPF > program please let me know. Did we find a solution to non-map redirect? Sorry if I missed the discussion, I couldn't make the iovisor call this week due to travel. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
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 + Saeed Mahameed 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=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 =devmap= already 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 ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
