netdev - Re: [PATCH iwl-next v2 0/4] igb: XDP/ZC follow up

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Message-ID: <Z7YaLuho0hXL7Jb1@LQ3V64L9R2>
Date: Wed, 19 Feb 2025 12:51:42 -0500
From: Joe Damato <jdamato@...tly.com>
To: Kurt Kanzenbach <kurt@...utronix.de>
Cc: Tony Nguyen <anthony.l.nguyen@...el.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Gerhard Engleder <gerhard@...leder-embedded.com>,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org
Subject: Re: [PATCH iwl-next v2 0/4] igb: XDP/ZC follow up

On Wed, Feb 19, 2025 at 03:03:36PM +0100, Kurt Kanzenbach wrote:
> On Tue Feb 18 2025, Joe Damato wrote:
> > On Tue, Feb 18, 2025 at 04:18:19PM -0500, Joe Damato wrote:
> >> On Mon, Feb 17, 2025 at 12:31:20PM +0100, Kurt Kanzenbach wrote:
> >> > This is a follow up for the igb XDP/ZC implementation. The first two 
> >> > patches link the IRQs and queues to NAPI instances. This is required to 
> >> > bring back the XDP/ZC busy polling support. The last patch removes 
> >> > undesired IRQs (injected via igb watchdog) while busy polling with 
> >> > napi_defer_hard_irqs and gro_flush_timeout set.
> >> > 
> >> > Signed-off-by: Kurt Kanzenbach <kurt@...utronix.de>
> >> > ---
> >> > Changes in v2:
> >> > - Take RTNL lock in PCI error handlers (Joe)
> >> > - Fix typo in commit message (Gerhard)
> >> > - Use netif_napi_add_config() (Joe)
> >> > - Link to v1: https://lore.kernel.org/r/20250210-igb_irq-v1-0-bde078cdb9df@linutronix.de
> >> 
> >> Thanks for sending a v2.
> >> 
> >> My comment from the previous series still stands, which simply that
> >> I have no idea if the maintainers will accept changes using this API
> >> or prefer to wait until Stanislav's work [1] is completed to remove
> >> the RTNL requirement from this API altogether.
> >
> > Also, may be worth running the newly added XSK test with the NETIF
> > env var set to the igb device? Assuming eth0 is your igb device:
> >
> >   NETIF=eth0 ./tools/testing/selftests/drivers/net/queues.py
> >
> > should output:
> >
> >   KTAP version 1
> >   1..4
> >   ok 1 queues.get_queues
> >   ok 2 queues.addremove_queues
> >   ok 3 queues.check_down
> >   ok 4 queues.check_xdp
> >   # Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0
> >
> > Note the check_xdp line above.
> >
> 
> Sure, why not. Seems to work.

Thanks for testing it.
 
> |root@...1:~/linux# uname -a
> |Linux apl1 6.14.0-rc2+ #2 SMP PREEMPT_RT Wed Feb 19 14:41:23 CET 2025 x86_64 GNU/Linux
> |root@...1:~/linux# NETIF=enp2s0 ./tools/testing/selftests/drivers/net/queues.py
> |KTAP version 1
> |1..4
> |ok 1 queues.get_queues
> |ok 2 queues.addremove_queues
> |ok 3 queues.check_down
> |ok 4 queues.check_xdp
> |# Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0
> 
> Has this xsk netlink attribute been added fairly recently? The test
> failed on my kernel from a few days ago (kernel from today works).

Yes, it was just merged, see the commit date here:

https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=788e52e2b66844301fe09f3372d46d8c62f6ebe4

> I think there's room for improvement though:
> 
> |root@...1:~/linux# NETIF=enp2s0 ./tools/testing/selftests/drivers/net/queues.py
> |KTAP version 1
> |1..4
> |ok 1 queues.get_queues
> |ok 2 queues.addremove_queues
> |ok 3 queues.check_down
> |# Exception| Traceback (most recent call last):
> |# Exception|   File "/root/linux/tools/testing/selftests/net/lib/py/ksft.py", line 218, in ksft_run
> |# Exception|     case(*args)
> |# Exception|   File "/root/linux/./tools/testing/selftests/drivers/net/queues.py", line 53, in check_xdp
> |# Exception|     ksft_eq(q['xsk'], {})
> |# Exception|             ~^^^^^^^
> |# Exception| KeyError: 'xsk'
> |not ok 4 queues.check_xdp
> |# Totals: pass:3 fail:1 xfail:0 xpass:0 skip:0 error:0
> 
> I'd assume this shouldn't be a Python exception, but rather say
> something like "Expected xsk attribute, but none found. Fix the driver!" :)
> 
> While at it would you mind to add a newline to the xdp_helper usage
> line (and fix the one typo)?

Jakub currently has a series out to change the test a bit and
improve it overall, see:

  https://lore.kernel.org/netdev/20250218195048.74692-1-kuba@kernel.org/

It looks like your concerns (the typo, newline, and better error)
may still remain. If so, I can submit a follow-up once his work has
been merged to address your concerns - unless you'd like to do
that?