netdev - Re: [PATCH v3 8/7] pppoatm: fix missing wakeup in pppoatm

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Date:	Sun, 11 Nov 2012 07:28:53 +0000
From:	David Woodhouse <dwmw2@...radead.org>
To:	Krzysztof Mazur <krzysiek@...lesie.net>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Chas Williams - CONTRACTOR <chas@....nrl.navy.mil>,
	davem@...emloft.net
Subject: Re: [PATCH v3 8/7] pppoatm: fix missing wakeup in pppoatm_send()

On Sat, 2012-11-10 at 21:23 +0100, Krzysztof Mazur wrote:
> With this tasklet_schedule() we implement a "spin_lock" here, but in
> this case both conditions (vcc not ready and socket locked) can be
> true for a long time and we can spin here for a long time. 

Reading this more carefully this morning... I hadn't realised it was
these conditions, and not the sock_owned_by_user(), which had triggered.
Yes, perhaps we should just return zero in that case and find another
wakeup trigger... if indeed a wakeup is ever required in the VF_RELEASED
and VF_CLOSE case. And if we've fixed things so that !VF_READY can never
happen (have we?).... perhaps this one doesn't matter at all? It was the
sock_owned_by_user() case I was most interested in, and I was expecting
that lock would generally be held briefly enough that the tasklet would
be fine. Was that not so?

-- 
dwmw2

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