linux-kernel - Re: [PATCH] net: Adjust softirq raising in __napi

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Message-ID: <20091026075438.GB6187@ff.dom.local>
Date:	Mon, 26 Oct 2009 07:54:38 +0000
From:	Jarek Poplawski <jarkao2@...il.com>
To:	Johannes Berg <johannes@...solutions.net>
Cc:	Tilman Schmidt <tilman@...p.cc>,
	David Miller <davem@...emloft.net>, hidave.darkstar@...il.com,
	linux-kernel@...r.kernel.org, tglx@...utronix.de,
	linux-wireless@...r.kernel.org, linux-ppp@...r.kernel.org,
	netdev@...r.kernel.org, paulus@...ba.org,
	Michael Buesch <mb@...sch.de>,
	Oliver Hartkopp <oliver@...tkopp.net>
Subject: Re: [PATCH] net: Adjust softirq raising in __napi_schedule

On Mon, Oct 26, 2009 at 08:44:14AM +0100, Johannes Berg wrote:
> On Mon, 2009-10-26 at 07:41 +0000, Jarek Poplawski wrote:
> 
> > > netif_rx_ni() disables preemption.
> > 
> > You wrote earlier:
> > 
> > > [...] the networking layer needs to have
> > > packets handed to it with softirqs disabled.
> > 
> > How disabling preemption can fix something which needs softirqs
> > disabled? Could you be more precise?
> 
> No, I wrote that I didn't know. I suppose now that I looked at it I do
> know, and only disabling preemption is required.

But netif_rx has preemption disabled most of the time (by hardirqs
disabling). So maybe disabling preemption isn't the main reason here
either?

Jarek P.
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