netdev - Re: [PATCH v2] VLAN, support ingress/egress priority map flushing

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Date:   Mon, 13 Mar 2017 08:28:38 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Thierry Du Tre <thierry@...ystems.be>
Cc:     netdev@...r.kernel.org, Ben Greear <greearb@...delatech.com>
Subject: Re: [PATCH v2] VLAN, support ingress/egress priority map flushing

On Mon, 2017-03-13 at 15:36 +0100, Thierry Du Tre wrote:

> +void vlan_dev_flush_egress_priority(const struct net_device *dev)
> +{
> +	struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
> +	struct vlan_priority_tci_mapping *mp;
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
> +		while ((mp = vlan->egress_priority_map[i]) != NULL) {
> +			vlan->egress_priority_map[i] = mp->next;
> +			kfree(mp);
> +		}
> +	}
> +	vlan->nr_egress_mappings = 0;
> +}


Are you doing this on a live device ?

Looks you'll need proper RCU support then.

Otherwise, crashes will happen, say in egress_priority_map()

smp_rmb() wont be enough if items can now be destroyed.