[ofa-general] NetEffect, iw_nes and kernel warning
Roland Dreier
rdreier at cisco.com
Fri Jan 30 09:35:52 PST 2009
> > OK, thanks... what confused me is that several other drivers also do
> > skb_linearize() in their hard_start_xmit method... eg bnx2x,
> > via-velocity, mv643xx_eth. So there are several other lurking bugs to
> > deal with here I guess.
>
> I don't know about the rest but bnx2x is certainly OK since it
> only does so with IRQ enabled. It is legal to call skb_linearize
> as long as you're sure that IRQs are enabled, which is always the
> case for hard_start_xmit upon entry.
I don't believe this is accurate. Calling skb_linearize() (on a kernel
with CONFIG_HIGHMEM set) can end up calling local_bh_enable() in
kunmap_skb_frag(), which can obviously cause problems if the initial
context relies on having BHs disabled (as hard_start_xmit does).
- R.
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