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Subject: Re: softirqs are invoked while bottom halves are masked
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Thomas De Schampheleire <patrickdepinguin+linuxppc@gmail.com>
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Date: Wed, 13 Jul 2011 09:38:53 +0200
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Cc: linuxppc-dev@ozlabs.org, netdev@vger.kernel.org, afleming@freescale.com,
	David Miller <davem@davemloft.net>, ronny.meeus@gmail.com
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Le mercredi 13 juillet 2011 à 09:20 +0200, Thomas De Schampheleire a
écrit :

> I just want to mention that, although you seem to think that we
> shouldn't have created this thread in the first place, your and Eric's
> remarks have actually helped us in identifying the problem and
> increasing our understanding.
> 

Thread was fine IMHO, but should have mentioned the context of "non
standard linux-2.6 or net-next-2.6 trees"

I would like to mention NETIF_F_LLTX existence.

While being marked deprecated, it allows a lockless tx path :

The device transmit handler can then perform custom actions, including
its own locking if needed.

If the user wants a specific Qdisc setup (instead of a no qdisc one), it
still can.

veth, loopback, dummy, macvlan & bond devices use NETIF_F_LLTX for
example.

But ndo_start_xmit() must always be called with BH disabled.