Eryk reported an issue that I have put under Closes: tag, related to
umem addrs being prematurely produced onto pool's completion queue.
Let us make the skb's destructor responsible for producing all addrs
that given skb used.

Introduce struct xsk_addrs which will carry descriptor count with array
of addresses taken from processed descriptors that will be carried via
skb_shared_info::destructor_arg. This way we can refer to it within
xsk_destruct_skb(). In order to mitigate the overhead that will be
coming from memory allocations, let us introduce kmem_cache of
xsk_addrs. There will be a single kmem_cache for xsk generic xmit on the
system.

Commit from fixes tag introduced the buggy behavior, it was not broken
from day 1, but rather when xsk multi-buffer got introduced.

Fixes: b7f72a3 ("xsk: introduce wrappers and helpers for supporting multi-buffer in Tx path")
Reported-by: Eryk Kubanski <[email protected]>
Closes: https://lore.kernel.org/netdev/[email protected]/
Acked-by: Magnus Karlsson <[email protected]>
Signed-off-by: Maciej Fijalkowski <[email protected]>
Acked-by: Stanislav Fomichev <[email protected]>