From: David Ahern <dsahern@gmail.com>
To: Andrii Nakryiko <andriin@fb.com>,
bpf@vger.kernel.org, netdev@vger.kernel.org, ast@fb.com,
daniel@iogearbox.net
Cc: andrii.nakryiko@gmail.com, kernel-team@fb.com,
"Jakub Kicinski" <kicinski@fb.com>,
"Andrey Ignatov" <rdna@fb.com>,
"Takshak Chahande" <ctakshak@fb.com>,
"Toke Høiland-Jørgensen" <toke@redhat.com>
Subject: Re: [PATCH bpf-next 4/7] bpf: implement BPF XDP link-specific introspection APIs
Date: Mon, 13 Jul 2020 08:32:30 -0600 [thread overview]
Message-ID: <7a68d9cc-f8dc-a11f-f1d4-7307519be866@gmail.com> (raw)
In-Reply-To: <20200710224924.4087399-5-andriin@fb.com>
On 7/10/20 4:49 PM, Andrii Nakryiko wrote:
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 025687120442..a9c634be8dd7 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -8973,6 +8973,35 @@ static void bpf_xdp_link_dealloc(struct bpf_link *link)
> kfree(xdp_link);
> }
>
> +static void bpf_xdp_link_show_fdinfo(const struct bpf_link *link,
> + struct seq_file *seq)
> +{
> + struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
> + u32 ifindex = 0;
> +
> + rtnl_lock();
> + if (xdp_link->dev)
> + ifindex = xdp_link->dev->ifindex;
> + rtnl_unlock();
Patch 2 you set dev but don't hold a refcnt on it which is why you need
the locking here. How do you know that the dev pointer is even valid here?
If xdp_link is going to have dev reference you need to take the refcnt
and you need to handle NETDEV notifications to cleanup the bpf_link when
the device goes away.
next prev parent reply other threads:[~2020-07-13 14:32 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200710224924.4087399-1-andriin@fb.com>
[not found] ` <20200710224924.4087399-3-andriin@fb.com>
2020-07-13 14:19 ` [PATCH bpf-next 2/7] bpf, xdp: add bpf_link-based XDP attachment API David Ahern
2020-07-13 22:33 ` Andrii Nakryiko
2020-07-14 13:57 ` Toke Høiland-Jørgensen
2020-07-14 18:59 ` Andrii Nakryiko
2020-07-14 20:12 ` Toke Høiland-Jørgensen
2020-07-14 20:37 ` Andrii Nakryiko
2020-07-14 21:41 ` Toke Høiland-Jørgensen
2020-07-14 22:26 ` Andrii Nakryiko
2020-07-15 15:48 ` Toke Høiland-Jørgensen
2020-07-15 20:54 ` Andrii Nakryiko
2020-07-16 10:52 ` Toke Høiland-Jørgensen
2020-07-22 6:45 ` Andrii Nakryiko
[not found] ` <20200710224924.4087399-5-andriin@fb.com>
2020-07-13 14:32 ` David Ahern [this message]
2020-07-13 22:41 ` [PATCH bpf-next 4/7] bpf: implement BPF XDP link-specific introspection APIs Andrii Nakryiko
2020-07-13 5:12 [PATCH bpf-next 0/7] BPF XDP link Andrii Nakryiko
2020-07-13 5:12 ` [PATCH bpf-next 4/7] bpf: implement BPF XDP link-specific introspection APIs Andrii Nakryiko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7a68d9cc-f8dc-a11f-f1d4-7307519be866@gmail.com \
--to=dsahern@gmail.com \
--cc=andrii.nakryiko@gmail.com \
--cc=andriin@fb.com \
--cc=ast@fb.com \
--cc=bpf@vger.kernel.org \
--cc=ctakshak@fb.com \
--cc=daniel@iogearbox.net \
--cc=kernel-team@fb.com \
--cc=kicinski@fb.com \
--cc=netdev@vger.kernel.org \
--cc=rdna@fb.com \
--cc=toke@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).