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Subject: Re: [GIT] Networking
From: Johannes Berg <johannes@sipsolutions.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>,
	"Grumbach, Emmanuel" <emmanuel.grumbach@intel.com>,
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Date: Fri, 13 Jun 2014 08:59:47 +0200
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On Fri, 2014-06-13 at 06:48 +0000, Linus Torvalds wrote:
> On Thu, Jun 12, 2014 at 12:14 PM, David Miller <davem@davemloft.net> wrote:
> >
> >   git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
> 
> Hmm. I get *lots* of the appended messages from iwlwifi now. Things
> still seem to work, but ...
> 
> This is a Haswell laptop with bog-standard intel wireless:
> 
>   01:00.0 Network controller: Intel Corporation Wireless 7260 (rev 6b)
> 
> Any ideas?

Looks odd.

If the stacktrace/message

> [  273.783438] <unknown>: hw csum failure
> [  273.783449] CPU: 2 PID: 2199 Comm: Chrome_IOThread Not tainted 3.15.0-11906-g6d87c225f5d8 #8
> [  273.783451] Hardware name: Sony Corporation SVP11213CXB/VAIO, BIOS R0270V7 05/17/2013
> [  273.783461] Call Trace:
> [  273.783477]  [<ffffffff8159d199>] ? dump_stack+0x41/0x51
> [  273.783488]  [<ffffffff814a4f1d>] ? skb_copy_and_csum_datagram_iovec+0xfd/0x110
> [  273.783494]  [<ffffffff8150e2ea>] ? udp_recvmsg+0x1ca/0x390
> [  273.783500]  [<ffffffff81518e95>] ? inet_recvmsg+0x65/0x80
> [  273.783506]  [<ffffffff814971f5>] ? sock_recvmsg+0x95/0xd0
> [  273.783511]  [<ffffffff81197862>] ? ep_send_events_proc+0xa2/0x1b0
> [  273.783513]  [<ffffffff811977c0>] ? ep_read_events_proc+0xb0/0xb0
> [  273.783516]  [<ffffffff81497325>] ? SYSC_recvfrom+0xb5/0x110
> [  273.783521]  [<ffffffff8108bdc0>] ? wake_up_state+0x10/0x10
> [  273.783527]  [<ffffffff815a3d92>] ? system_call_fastpath+0x16/0x1b

is to be believed, then I'm not sure why you think iwlwifi is involved
though.

Either way, iwlwifi doesn't support HW checksumming, so it failing makes
no sense, it's not there to start with.

The only thing that touched this seems to be Tom's patch:

commit 7e3cead5172927732f51fde77fef6f521e22f209
Author: Tom Herbert <therbert@google.com>
Date:   Tue Jun 10 18:54:19 2014 -0700

    net: Save software checksum complete

but I'm not familiar enough to say where this leads.

If it's iwlwifi, then maybe that commit broke something with devices
that don't support checksumming?

johannes