Bug 194569 - TCP: wlp1s0: Driver has suspect GRO implementation, TCP performance may be compromised.
Summary: TCP: wlp1s0: Driver has suspect GRO implementation, TCP performance may be co...
Status: NEW
Alias: None
Product: Drivers
Classification: Unclassified
Component: network-wireless (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: drivers_network-wireless@kernel-bugs.osdl.org
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-02-12 22:39 UTC by Cristian Aravena Romero
Modified: 2018-06-08 15:40 UTC (History)
6 users (show)

See Also:
Kernel Version: Ubuntu 4.9.0-15.16-generic 4.9.5
Tree: Mainline
Regression: No


Attachments

Description Cristian Aravena Romero 2017-02-12 22:39:08 UTC
Open bug in launchpad.net
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1664072

"dmesg:
[ 7578.057461] TCP: wlp1s0: Driver has suspect GRO implementation, TCP performance may be compromised."
Comment 1 Fabio Pedretti 2018-06-05 12:03:22 UTC
This harmless warning should be fixed backporting [0] to 4.9 series.

[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0b9aefea860063bb39e36bd7fe6c7087fed0ba87
Comment 2 Marcelo Ricardo Leitner 2018-06-08 15:15:25 UTC
I went over iwlwifi commits since then and I couldn't find any issue regarding TCP/GSO. That said, I agree that it seems to be harmless in that setup and that backporting 0b9aefea860063bb39e36bd7fe6c7087fed0ba87 should help on identifying if it's a false-positive or not.

Someone needs to send an email to netdev@ asking for it, though. kernel bugzilla is not how it's done for networking subsystem. More info in ./Documentation/networking/netdev-FAQ.txt . Thanks.
Comment 3 Fabio Pedretti 2018-06-08 15:40:05 UTC
BTW, I had this same warning with vmxnet3 driver with 4.9. I tried a newer kernel and the message didn't appear. I posted my findings here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=864642#95 - for reference:

===
It looks like the warning appeared with this first commit:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=dcb17d22e1c2cd72e72190c736349a675362b3bc
but was later corrected with this second one:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0b9aefea860063bb39e36bd7fe6c7087fed0ba87

The first commit was merged in the 4.9 tree, but not the second one (at least not up to 4.9.106), and was only merged in 4.11.

So I would conclude the warning may be harmless, unless you got it on a >= 4.11 kernel. And I also verified I don't get it on such a newer kernel.

I would close this bug, but it may eventually be nice to backport the second commit in 4.9 to avoid the harmless warning.
===

Searching on the net, there are other reports with the same issue and with various other drivers.

I added in CC: here the net/ipv4 maintainers I found in MAINTAINERS file:

NETWORKING [IPv4/IPv6]
M:	"David S. Miller" <davem@davemloft.net>
M:	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
M:	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
L:	netdev@vger.kernel.org
T:	git git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git
S:	Maintained
F:	net/ipv4/
F:	net/ipv6/
F:	include/net/ip*
F:	arch/x86/net/*

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