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

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Date:	Fri, 30 Nov 2012 18:00:07 +0100
From:	Krzysztof Mazur <krzysiek@...lesie.net>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	"Chas Williams (CONTRACTOR)" <chas@....nrl.navy.mil>,
	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 Fri, Nov 30, 2012 at 04:23:46PM +0000, David Woodhouse wrote:
> 
> +static void br2684_release_cb(struct atm_vcc *atmvcc)
> +{
> +	struct br2684_vcc *brvcc = BR2684_VCC(atmvcc);
> +
> +	/*
> +	 * A race with br2684_xmit_vcc() might cause a spurious wakeup just
> +	 * after that function *stops* the queue, and qspace might actually
> +	 * go negative before the queue stops again. We cope with that.
> +	 */

We cannot race with br2684_xmit_vcc() because both br2684_xmit_vcc()
and br2684_release_cb() are called with locked sk->sk_lock.slock.

> +	if (atomic_read(&brvcc->qspace) > 0)
> +		netif_wake_queue(brvcc->device);
> +
> +	if (brvcc->old_release_cb)
> +		brvcc->old_release_cb(atmvcc);
> +}

Except that comment, the patch looks good:

Acked-by: Krzysztof Mazur <krzysiek@...lesie.net>

Krzysiek
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