From: Jakub Kicinski <kuba@kernel.org>
To: Ding Meng <meng.ding@siemens.com>
Cc: netdev@vger.kernel.org,
Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@kernel.org>,
Paolo Abeni <pabeni@redhat.com>, Jonathan Corbet <corbet@lwn.net>,
Andrew Lunn <andrew+netdev@lunn.ch>,
Tony Nguyen <anthony.l.nguyen@intel.com>,
Przemek Kitszel <przemyslaw.kitszel@intel.com>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Richard Cochran <richardcochran@gmail.com>,
florian.bezdeka@siemens.com, jan.kiszka@siemens.com,
wq.wang@siemens.com, p@1g4.org, gerhard@engleder-embedded.com,
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Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
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Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
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linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
intel-wired-lan@lists.osuosl.org,
linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH] net: mark skb NAPI IDs independently of busy polling
Date: Fri, 13 Nov 2026 15:28:21 -0800 [thread overview]
Message-ID: <20261113152821.47e9d219@kernel.org> (raw)
In-Reply-To: <4pqljild2fp6eotiicvwbwu2wfw66fzd4qamwt6utirdjxlaok@iiu2f3k7azrp>
On Thu, 12 Nov 2026 12:33:57 +0800 Ding Meng wrote:
> On Tue, Nov 10, 2026 at 01:45:39PM -0800, Jakub Kicinski wrote:
> > On Thu, 5 Nov 2026 15:16:08 +0800 Ding Meng wrote:
> > > + interface index will be returned only if CONFIG_SKB_MARK_NAPI_ID is
> > > + enabled and the driver is using NAPI. This hidden configuration is
> > > + selected automatically by busy-poll support and by drivers that need
> > > + skb NAPI IDs to resolve deferred hardware timestamps. Drivers that
> > > + use deferred timestamp conversion must select it so the networking
> > > + stack can find the device and call its timestamp callback even when
> > > + busy polling is disabled. The struct contains also two other fields,
> > > + but they are reserved and undefined.
> >
> > Just take napi_id from under CONFIG_NET_RX_BUSY_POLL instead of
> > complicating everyone's lives.
> > --
> > pw-bot: cr
>
> When BUSY_POLL is n under PREEMPT_RT && NETCONSOLE, igc fails to get RX
> hardware timestamps.
>
> Then, drivers that use deferred timestamp conversion (e.g. igc, engleder) must
> specify a busy poll dependency if they want to obtain the original net
> device upon consuming the skb. However, this dependency is far from
> obvious, and annotating it for future features of this kind will be very
> hard to discover.
>
> Configuring the skb napi ID separately
> from busy poll seems cleaner and more reasonable.
"take from under" == make it always compiled in
prev parent reply other threads:[~2026-11-13 23:28 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-05 7:16 [PATCH] net: mark skb NAPI IDs independently of busy polling Ding Meng
2026-11-05 8:04 ` bot+bpf-ci
2026-11-05 8:04 ` bot+bpf-ci
2026-11-05 18:36 ` Jacob Keller
2026-11-05 22:29 ` Paul Moses
2026-11-06 2:03 ` Paul Moses
2026-11-06 5:50 ` Ding Meng
2026-11-06 6:36 ` Paul Moses
2026-11-10 19:32 ` Gerhard Engleder
2026-11-10 21:45 ` Jakub Kicinski
2026-11-12 4:33 ` Ding Meng
2026-11-13 8:29 ` Paul Moses
2026-11-13 20:59 ` Gerhard Engleder
2026-11-13 23:28 ` Jakub Kicinski [this message]
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