Re: [PATCH] solos-pci: don't call vcc->pop() after pclose()

From: David Woodhouse <dwmw2@infradead.org>
To: Krzysztof Mazur <krzysiek@podlesie.net>
Cc: David Laight <David.Laight@ACULAB.COM>,
	chas williams - CONTRACTOR <chas@cmf.nrl.navy.mil>,
	davem@davemloft.net, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, nathan@traverse.com.au
Subject: Re: [PATCH] solos-pci: don't call vcc->pop() after pclose()
Date: Thu, 29 Nov 2012 12:57:17 +0000	[thread overview]
Message-ID: <1354193837.21562.159.camel@shinybook.infradead.org> (raw)
In-Reply-To: <20121129124344.GA7704@shrek.podlesie.net>

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On Thu, 2012-11-29 at 13:43 +0100, Krzysztof Mazur wrote:
> 
> Removing packets from tx_queue is not needed. We can transmit packets
> also after close. We just can't call vcc->pop() after close,
> so we can just set SKB_CB(skb)->vcc of such packets to NULL so
> fpga_tx() won't call vcc->pop().

Your patch doesn't do that, does it? You'd want something like

 if (card->tx_skb[port] && SKB_CB(card->tx_skb[port]->vcc) == vcc)
    SKB_CB(card->tx_skb[port]->vcc) = NULL;

Under card->tx_lock should suffice.

And do we just *not* call the ->pop() on that skb ever? And hope that it
doesn't screw up some other state somewhere? Like if we're doing MLPPP
and I've implemented BQL for PPP... we might never call
ppp_completed_queue() for that skb, so even though this *channel* is
going away, it might still contribute towards the perceived queue on the
overall PPP netdev?

Failing to call ->pop() could cause memory leaks and other issues; I
don't think it's reasonable. I think we *have* to wait for
card->tx_skb[port] if it's for the VCC we're closing.

-- 
dwmw2

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