netdev - Re: [PATCH] net/davinci: do not use all descriptors for tx packets

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Date:	Tue, 03 Jan 2012 13:51:41 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	s.hauer@...gutronix.de
Cc:	netdev@...r.kernel.org, anantgole@...com, srk@...com
Subject: Re: [PATCH] net/davinci: do not use all descriptors for tx packets

From: Sascha Hauer <s.hauer@...gutronix.de>
Date: Tue,  3 Jan 2012 16:27:47 +0100

> The driver uses a shared pool for both rx and tx descriptors.
> During open it queues fixed number of 128 descriptors for receive
> packets. For each received packet it tries to queue another
> descriptor. If this fails the descriptor is lost for rx.
> The driver has no limitation on tx descriptors to use, so it
> can happen during a nmap / ping -f attack that the driver
> allocates all descriptors for tx and looses all rx descriptors.
> The driver stops working then.
> To fix this limit the number of tx descriptors used to half of
> the descriptors available, the rx path uses the other half.
> 
> Tested on a custom board using nmap / ping -f to the board from
> two different hosts.
> 
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>

Applied to net-next, thanks.

Well, at this point there is not logical reason to have a shared
descriptor pool unless the hardware requires it.  Does it?
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