[lkml]   [2001]   [Nov]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] ppp_generic causes skput:under: w/ pppoatm and vc-encaps
Hi Michal,

it is the receive side - (chan.hdrlen is set correctly) -- on the receive side
you'll the SKB from the device AND headroom is up to the device...
Michal Ostrowski wrote:

> If you set the hdrlen field of the ppp_channel that pppoatm registers
> (pvcc->chan.hdrlen, in pppoatm_assign_vcc()) then ppp_generic will
> always over-allocate skb space to allow for extra headers to be pushed
> in. This mechanism was put is so that we wouldn't have to copy the
> frame in order to slap on PPPoE headers onto it. I think it's a good
> idea to be doing this, especially if you're going to play with
> hard_header_len.
> If you look at pppoatm_send(), you'll see that you do an
> skb_realloc_headroom if there's no space for the headers. If
> pvcc->chan.hdrlen is set properly then this will be the exceptional,
> rather than the common case.
> > Here is my "better fix". In pppoatm, we should be increasing the
> > device header length appropriately. ie. dev->hard_header_len needs to
> > be increased in the pppoatm driver when vc-encaps is used.
> >
> > Franks a lot,
> > David S. Miller
> >
> --
> Michal Ostrowski

Till Immanuel Patzschke mailto:
interNetwork AG Phone: +49-(0)611-1731-121
Bierstadter Str. 7 Fax: +49-(0)611-1731-31
D-65189 Wiesbaden Web:

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:13    [W:0.103 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site