From: Roland Dreier <rdreier@cisco•com>
To: Stephen Hemminger <shemminger@vyatta•com>
Cc: netdev@vger•kernel.org, David Miller <davem@davemloft•net>,
general@lists•openfabrics.org
Subject: Re: [ofa-general] NetEffect, iw_nes and kernel warning
Date: Wed, 28 Jan 2009 13:52:15 -0800 [thread overview]
Message-ID: <adawscfumi8.fsf@cisco.com> (raw)
In-Reply-To: <20090128110514.2191c7a8@extreme> (Stephen Hemminger's message of "Wed, 28 Jan 2009 11:05:14 -0800")
> > 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.
> They all look like lurking (and untested) bug paths. mv643xx is especially
> bad since it can leak skb. But it should be possible to call pull_tail
> if bh is disabled (as long as irqs are enabled).
Yes. The only obvious problem with __pskb_pull_tail() with BHs disabled
is that with CONFIG_HIGHMEM set, it goes into kmap_skb_frag(), which
then unconditionally does local_bh_disable()/local_bh_enable(). There's
no reason in principle that kmap_skb_frag() couldn't do
local_save_flags()/local_restore_flags() instead.
Just grepping around I see other potential issues related to this, for
example the (unused but exported) function fcoe_fc_crc() does
kmap_atomic(KM_SKB_DATA_SOFTIRQ) without any particular BH disabling,
which might run into trouble if used in the wrong context...
- R.
next prev parent reply other threads:[~2009-01-28 21:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <497EF9AC.70104@poczta.onet.pl>
2009-01-27 23:53 ` [ofa-general] NetEffect, iw_nes and kernel warning Roland Dreier
2009-01-28 0:07 ` David Miller
2009-01-28 0:17 ` Stephen Hemminger
2009-01-28 16:36 ` Tung, Chien Tin
2009-01-28 18:05 ` Roland Dreier
2009-01-28 19:05 ` Stephen Hemminger
2009-01-28 21:52 ` Roland Dreier [this message]
2009-01-30 6:57 ` Herbert Xu
2009-01-30 8:22 ` Eilon Greenstein
2009-01-30 16:25 ` Stephen Hemminger
2009-01-30 17:35 ` Roland Dreier
2009-01-30 21:51 ` David Miller
2009-01-31 3:54 ` Roland Dreier
2009-04-21 9:09 ` Lennert Buytenhek
2009-04-21 12:49 ` Herbert Xu
2009-04-21 12:50 ` Herbert Xu
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