netdev - Re: oh crap... (re: %p6)

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Date:	Wed, 29 Oct 2008 10:24:42 -0700
From:	Harvey Harrison <harvey.harrison@...il.com>
To:	Joe Perches <joe@...ches.com>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: oh crap... (re: %p6)

On Wed, 2008-10-29 at 08:39 -0700, Joe Perches wrote:
> On Wed, 2008-10-29 at 07:55 -0700, Harvey Harrison wrote:
> > On Wed, 2008-10-29 at 01:54 -0700, David Miller wrote:
> > > I think we'll need to revert all of this or find some fix soon.  GCC
> > > warns about %p with a '#' flag modifier it seems :-(
> > > 
> > > net/ipv6/ip6_flowlabel.c: In function 'ip6fl_seq_show':
> > > net/ipv6/ip6_flowlabel.c:707: warning: '#' flag used with '%p' printf format
> > 
> > The easiest would be to pick a separate modifier for the raw case.  Or
> > revert the removal of NIP6_SEQFMT, I'll shoot you a patch shortly,
> > any preference in what modifier should be used?
> 
> I'd prefer something visual that represents "no colon".
> 
> Maybe %p6-: 

Putting a modifier after the format specifier seems a little strange to me.  But
I'm not sure if I can think of something that's too much better, currently I
was thinking of:

%pI6, %pi6
	%pI6 would act just like %p6
	%pi6 would act just like %#p6

Eventually %pI4 could be added as well. Which would print out the dot-separated
format.

Either that or add a %px<bytes> that prints out raw hex for the number
of <bytes>, so %p6 would stay and %#p6 would become %px16.  While this
is a bit uglier, it could be useful to others elsewhere in-kernel,
perhaps limited to 16 bytes or so.

Dave, I'll wait for your $0.02 before sending in a patch, but I have
both of the above implemented.

Harvey

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