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Re: [PATCH]: was Re: LLTX and netif_stop_queue

To: Lennert Buytenhek <buytenh@xxxxxxxxxxxxxx>
Subject: Re: [PATCH]: was Re: LLTX and netif_stop_queue
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
Date: Wed, 26 Jan 2005 22:32:47 -0800
Cc: shemminger@xxxxxxxx, roland@xxxxxxxxxxx, hadi@xxxxxxxxxx, iod00d@xxxxxx, eric.lemoine@xxxxxxxxx, netdev@xxxxxxxxxxx, ak@xxxxxxx, openib-general@xxxxxxxxxx, kaber@xxxxxxxxx
In-reply-to: <20050126132512.GA18220@xi.wantstofly.org>
References: <20050103171227.GD7370@esmail.cup.hp.com> <1104812294.1085.53.camel@jzny.localdomain> <20050119144711.3fdd3d93.davem@davemloft.net> <20050119151853.259de49a@dxpl.pdx.osdl.net> <20050119164640.6c67bdfa.davem@davemloft.net> <52r7kgu5n5.fsf@topspin.com> <20050119230526.393a5184.davem@davemloft.net> <20050120085611.33f9485e@dxpl.pdx.osdl.net> <20050121105452.GA12988@xi.wantstofly.org> <20050125222705.1ee878fd.davem@davemloft.net> <20050126132512.GA18220@xi.wantstofly.org>
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On Wed, 26 Jan 2005 14:25:12 +0100
Lennert Buytenhek <buytenh@xxxxxxxxxxxxxx> wrote:

> I've thought about this a bit, and the only sane way of doing recursion
> detection that doesn't involve 'struct net_device' would be to keep track
> of the recursion depth (perhaps per-CPU as you suggest) and tossing the
> packet when it exceeds some random value, right?

Yes, that's the idea.

> To reproduce the current behaviour more closely you'd have to keep a
> small per-CPU array of 'struct net_device *' pointers as a kind of
> recursion stack, and toss the packet when you hit a net_device that's
> already on the list.  But that seems like slight overkill.

Indeed.

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