From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] sh_eth: fix napi_{en|dis}able() calls racing against
 interrupts
Date: Wed, 04 Sep 2013 14:56:11 -0400 (EDT)
Message-ID: <20130904.145611.744777528462788964.davem@davemloft.net>
References: <201309040241.27834.sergei.shtylyov@cogentembedded.com>
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Cc: netdev@vger.kernel.org, nobuhiro.iwamatsu.yj@renesas.com,
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To: sergei.shtylyov@cogentembedded.com
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From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Date: Wed, 4 Sep 2013 02:41:27 +0400

> While implementing NAPI for the driver, I overlooked the race conditions where
> interrupt  handler might have called napi_schedule_prep() before napi_enable()
> was called or after napi_disable() was called. If RX interrupt happens, this
> would cause the endless interrupts and messages like:
> 
> sh-eth eth0: ignoring interrupt, status 0x00040000, mask 0x01ff009f.
> 
> The interrupt wouldn't even be masked by the kernel eventually since the handler
> would return IRQ_HANDLED all the time.
> 
> As a fix, move napi_enable() call before request_irq() call and napi_disable()
> call after free_irq() call.
> 
> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

Applied and queued up for -stable, thanks!