Message-ID: <47602B77.2090202@intel.com>
Date: Wed, 12 Dec 2007 10:41:59 -0800
From: "Kok, Auke" <auke-jan.h.kok@intel.com>
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To: David Miller <davem@davemloft.net>
CC: gallatin@myri.com, joonwpark81@gmail.com, netdev@vger.kernel.org,
       linux-kernel@vger.kernel.org, jgarzik@pobox.com,
       shemminger@linux-foundation.org,
       Jesse Brandeburg <jesse.brandeburg@intel.com>
Subject: Re: [RFC] net: napi fix
References: <47601A73.5010804@myri.com> <20071212.093819.205755031.davem@davemloft.net>
In-Reply-To: <20071212.093819.205755031.davem@davemloft.net>
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David Miller wrote:
> From: Andrew Gallatin <gallatin@myri.com>
> Date: Wed, 12 Dec 2007 12:29:23 -0500
> 
>> Is the netif_running() check even required?
> 
> No, it is not.
> 
> When a device is brought down, one of the first things
> that happens is that we wait for all pending NAPI polls
> to complete, then block any new polls from starting.

I think this was previously (pre-2.6.24) not the case, which is why e1000 et al
has this check as well and that's exactly what is causing most of the
net_rx_action oopses in the first place. Without the netif_running() check
previously the drivers were just unusable with NAPI and prone to many races with
down (i.e. touching some ethtool ioctl which wants to do a reset while routing
small packets at high numbers). that's why we added the netif_running() check in
the first place :)

There might be more drivers lurking that need this change...

Auke
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