linux-kernel - Re: [PATCH v2 3/3] pppoatm: protect against freeing of vcc

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Message-ID: <20121129105934.3e0c3a04@thirdoffive.cmf.nrl.navy.mil>
Date:	Thu, 29 Nov 2012 10:59:34 -0500
From:	chas williams - CONTRACTOR <chas@....nrl.navy.mil>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	Krzysztof Mazur <krzysiek@...lesie.net>,
	David Laight <David.Laight@...LAB.COM>, davem@...emloft.net,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	nathan@...verse.com.au
Subject: Re: [PATCH v2 3/3] pppoatm: protect against freeing of vcc

On Thu, 29 Nov 2012 15:47:57 +0000
David Woodhouse <dwmw2@...radead.org> wrote:


> @@ -1020,12 +1048,15 @@ static uint32_t fpga_tx(struct solos_card *card)
>  			if (vcc) {
>  				atomic_inc(&vcc->stats->tx);
>  				solos_pop(vcc, oldskb);
> -			} else {
> -				struct pkt_hdr *header = (void *)oldskb->data;
> -				if (le16_to_cpu(header->type) == PKT_PCLOSE)
> -					complete(&SKB_CB(oldskb)->c);
> +
> +				/*
> +				 * If it's a TX skb on a closed VCC, pclose()
> +				 * may be waiting for it...
> +				 */
> +				if (!test_bit(ATM_VF_READY, &vcc->flags))
> +					wake_up(&card->param_wq);
> +			} else
>  				dev_kfree_skb_irq(oldskb);
> -			}

the part that bothers me (and i dont have the programmer's guide for
the solos hardware) is that you are watching for the PKT_PCLOSE to be
sent to the card.  shouldnt you be watching for the PKT_PCLOSE to be
returned from the card (assuming it does such a thing) so that you can
be assured that the tx/rx for this vpi/vci pair has been "stopped"?
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