2018-04-24 18:56 GMT+02:00 Willem de Bruijn <willemdebruijn.ker...@gmail.com>:
> On Mon, Apr 23, 2018 at 9:56 AM, Björn Töpel <bjorn.to...@gmail.com> wrote:
>> From: Björn Töpel <bjorn.to...@intel.com>
>>
>> The xskmap is yet another BPF map, very much inspired by
>> dev/cpu/sockmap, and is a holder of AF_XDP sockets. A user application
>> adds AF_XDP sockets into the map, and by using the bpf_redirect_map
>> helper, an XDP program can redirect XDP frames to an AF_XDP socket.
>>
>> Note that a socket that is bound to certain ifindex/queue index will
>> *only* accept XDP frames from that netdev/queue index. If an XDP
>> program tries to redirect from a netdev/queue index other than what
>> the socket is bound to, the frame will not be received on the socket.
>>
>> A socket can reside in multiple maps.
>>
>> Signed-off-by: Björn Töpel <bjorn.to...@intel.com>
>
>> +struct xsk_map_entry {
>> + struct xdp_sock *xs;
>> + struct rcu_head rcu;
>> +};
>
>> +struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
>> +{
>> + struct xsk_map *m = container_of(map, struct xsk_map, map);
>> + struct xsk_map_entry *entry;
>> +
>> + if (key >= map->max_entries)
>> + return NULL;
>> +
>> + entry = READ_ONCE(m->xsk_map[key]);
>> + return entry ? entry->xs : NULL;
>> +}
>
> This dynamically allocated structure adds an extra cacheline lookup. If
> xdp_sock gets an rcu_head, it can be linked into the map directly.
Nice one! I'll try this out!
