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Re: [PATCH 1/2 2.6] e100: fix NAPI race with watchdog

To: jesse.brandeburg@xxxxxxxxx
Subject: Re: [PATCH 1/2 2.6] e100: fix NAPI race with watchdog
From: James Chapman <jchapman@xxxxxxxxxxx>
Date: Thu, 23 Sep 2004 10:08:48 +0100
Cc: jgarzik@xxxxxxxxx, netdev@xxxxxxxxxxx
Sender: netdev-bounce@xxxxxxxxxxx
User-agent: Internet Messaging Program (IMP) 3.2.2
> While polling in NAPI mode, we were occassionally getting interrupts
> re-enabled by the watchdog trying to generate a software interrupt.
> Fix is to add a spinlock around that shared hardware register to
> allow a read-modify-write operation.  This was nasty nasty.  I don't
> like the spinlock in the hot path but i see no other way.  Comments
> are welcome.

While working with NAPI on the e100 a while ago, I seriously
considered removing the generation of the sw interrupt altogether for
the NAPI case. Does it serve any purpose? NAPI is polling the driver
already anyway.

/james







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