From: Jakub Kicinski <kuba@kernel.org>
To: Hangbin Liu <liuhangbin@gmail.com>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Jiri Pirko <jiri@resnulli.us>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Lorenzo Bianconi <lorenzo@kernel.org>,
Andrii Nakryiko <andriin@fb.com>, Jussi Maki <joamaki@gmail.com>,
Jay Vosburgh <jv@jvosburgh.net>,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
Liang Li <liali@redhat.com>
Subject: Re: [PATCH net] bpf: xdp: fallback to SKB mode if DRV flag is absent.
Date: Tue, 15 Oct 2024 08:51:21 -0700 [thread overview]
Message-ID: <20241015085121.5f22e96f@kernel.org> (raw)
In-Reply-To: <20241015033632.12120-1-liuhangbin@gmail.com>
On Tue, 15 Oct 2024 03:36:32 +0000 Hangbin Liu wrote:
> After commit c8a36f1945b2 ("bpf: xdp: Fix XDP mode when no mode flags
> specified"), the mode is automatically set to XDP_MODE_DRV if the driver
> implements the .ndo_bpf function. However, for drivers like bonding, which
> only support native XDP for specific modes, this may result in an
> "unsupported" response.
>
> In such cases, let's fall back to SKB mode if the user did not explicitly
> request DRV mode.
Looks like the issue is reported by QA rather than a real user.
A weak -1 from me on building such unreliable heuristics into
the kernel. As BPF CI's failure points out the ops can return
EOPNOTSUPP for multiple reasons while dev_xdp_mode() only checks
if the driver *has* ndo_bpf, not if it fails.
prev parent reply other threads:[~2024-10-15 15:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-15 3:36 [PATCH net] bpf: xdp: fallback to SKB mode if DRV flag is absent Hangbin Liu
2024-10-15 8:17 ` Daniel Borkmann
2024-10-15 9:53 ` Nikolay Aleksandrov
2024-10-15 10:38 ` Hangbin Liu
2024-10-15 10:46 ` Nikolay Aleksandrov
2024-10-15 10:55 ` Nikolay Aleksandrov
2024-10-15 11:31 ` Hangbin Liu
2024-10-15 15:51 ` Jakub Kicinski [this message]
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