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Message-Id: <20120903.134956.712552224937949341.davem@davemloft.net>
Date: Mon, 03 Sep 2012 13:49:56 -0400 (EDT)
From: David Miller <davem@...emloft.net>
To: bjorn@...k.no
Cc: netdev@...r.kernel.org, linux-usb@...r.kernel.org,
ming.lei@...onical.com, oneukum@...e.de
Subject: Re: [PATCH net] net: usbnet: fix softirq storm on suspend
From: Bjørn Mork <bjorn@...k.no>
Date: Mon, 3 Sep 2012 10:26:18 +0200
> Suspending an open usbnet device results in constant
> rescheduling of usbnet_bh.
>
> commit 65841fd5 "usbnet: handle remote wakeup asap"
> refactored the usbnet_bh code to allow sharing the
> urb allocate and submit code with usbnet_resume. In
> this process, a test for, and immediate return on,
> ENOLINK from rx_submit was unintentionally dropped.
>
> The rx queue will not grow if rx_submit fails,
> making usbnet_bh reschedule itself. This results
> in a softirq storm if the error is persistent.
> rx_submit translates the usb_submit_urb error
> EHOSTUNREACH into ENOLINK, so this is an expected
> and persistent error for a suspended device. The
> old code tested for this condition and avoided
> rescheduling. Putting this test back.
>
> Cc: <stable@...r.kernel.org> # v3.5
> Cc: Ming Lei <ming.lei@...onical.com>
> Cc: Oliver Neukum <oneukum@...e.de>
> Signed-off-by: Bjørn Mork <bjorn@...k.no>
Applied, thanks.
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