netdev - Re: [RFC PATCH bpf-next 4/4] libbpf: don't remove eBPF resources when other xsks are present

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Message-ID: <D5F7F7EF-5B29-482E-BB6F-52A701A005B3@gmail.com>
Date:   Mon, 03 Jun 2019 11:26:01 -0700
From:   "Jonathan Lemon" <jonathan.lemon@...il.com>
To:     "Maciej Fijalkowski" <maciejromanfijalkowski@...il.com>
Cc:     magnus.karlsson@...el.com, bjorn.topel@...el.com,
        netdev@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        jakub.kicinski@...ronome.com, songliubraving@...com
Subject: Re: [RFC PATCH bpf-next 4/4] libbpf: don't remove eBPF resources when
 other xsks are present

On 3 Jun 2019, at 6:19, Maciej Fijalkowski wrote:

> In case where multiple xsk sockets are attached to a single interface
> and one of them gets detached, the eBPF maps and program are removed.
> This should not happen as the rest of xsksocks are still using these
> resources.

I'm not seeing that behavior - each xsk holds it's own reference to
xsks_maps, so when the map descriptor is closed, it doesn't necessarily
delete the map.

There's no refcount on the bpf program though; so the socket should not
be trying to remove the program - that should be done by the application.
-- 
Jonathan