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Message-ID: <1437332822.24289.19.camel@perches.com>
Date: Sun, 19 Jul 2015 12:07:02 -0700
From: Joe Perches <joe@...ches.com>
To: David Miller <davem@...emloft.net>
Cc: sowmini.varadhan@...cle.com, netdev@...r.kernel.org,
alexander.duyck@...il.com
Subject: Re: [PATCHv2 RFC net-next] net/vxlan: Fix kernel unaligned access
in __vxlan_find_mac
On Sun, 2015-07-19 at 11:38 -0700, David Miller wrote:
> From: Sowmini Varadhan <sowmini.varadhan@...cle.com>
> Date: Sun, 19 Jul 2015 14:01:34 +0200
>
> > On 07/18/2015 08:06 PM, Joe Perches wrote:
> >
> >> It seems that this code has had unaligned accesses
> >> on this field even before compare_ether_addr was
> >> converted to ether_addr_equal.
> >>
> >> Is sparc64 the only one that emits / ratelimits that
> >> unaligned access message? I looked a little, but I
> >> didn't find a fixup message when MIPS does unaligned
> >> accesses. Are all the other arches silent when
> >> fixing up unaligned accesses? Maye adding a generic
> >> debug only ratelimited message might help remove
> >> more of these. As it's not fatal, naybe the sparc64
> >> message should be KERN_DEBUG/pr_debug.
> >
> > I'm confused, are we suggesting that we "fix" the unaligned
> > access by snuffing out the message that complains loudly and correctly
> > about it?
> >
> > See also: large block comment above __pksb_trim
> > about correctly using skb_reserve(). Evidently not being
> > correctly done for the IPv6-vxlan code path (and possibly
> > for other encaps too?)
>
> We should fix the unaligned accesses, rather than quiet the
> warning.
Definitely so, the question I have is whether or not the the
message should be able to be silenced, not just ratelimited.
I think there are likely to be occasions when, given arbitrary
protocol stacking, unaligned accesses are unavoidable.
Perhaps batman might have this as an actual issue.
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