netdev - Re: [PATCH] net: Fix race condition on receive path.

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Message-ID: <20100305132118.1855617a@nehalam>
Date:	Fri, 5 Mar 2010 13:21:18 -0800
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Daniel Walker <dwalker@...eaurora.org>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Jim Harford <c_jharfo@...cinc.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] net: Fix race condition on receive path.

On Fri, 05 Mar 2010 11:34:59 -0800
Daniel Walker <dwalker@...eaurora.org> wrote:

> Fixes a race condition on the networking receive path that causes all
> received packets to be dropped after 15-60 minutes of heavy network usage.
> Function process_backlog() empties the receive queue, re-enables
> interrupts, then "completes" the softIRQ.  This provides a time window for
> netif_rx() to execute (in IRQ context) and enqueue a received packet
> without re-scheduling the softIRQ.  After this, the receive queue is never
> processed and the system eventually begins to drop all received packets.

I wonder why this hasn't shown up before?

Where exactly is the window between empty process_backlog and netif_rx?

Maybe it is ARM specific behavior of softirq?
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