Re: Resource management for ndo_xdp_xmit (Was: [PATCH net] virtio_net: Account for tx bytes and packets on sending xdp_frames)

["Toke Høiland-Jørgensen" <toke@redhat.com>]

Jakub Kicinski <jakub.kicinski@netronome.com> writes:

> On Sat, 9 Feb 2019 00:18:31 +0000, Saeed Mahameed wrote:
>> On Fri, 2019-02-08 at 15:17 -0800, Saeed Mahameed wrote:
>> > On Thu, 2019-02-07 at 19:08 +0000, 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?

See my other reply to Saeed :)

-Toke