On Mon, Mar 14, 2022 at 10:52:20AM +0100, Tobias Waldekranz wrote:
> +int br_mst_fill_info(struct sk_buff *skb, struct net_bridge_vlan_group *vg)
> +{
> + struct net_bridge_vlan *v;
> + struct nlattr *nest;
> + unsigned long *seen;
> + int err = 0;
> +
> + seen = bitmap_zalloc(VLAN_N_VID, 0);
I see there is precedent in the bridge driver for using dynamic
allocation as opposed to on-stack declaration using DECLARE_BITMAP().
I imagine this isn't just to be "heapsters", but why?
I don't have a very good sense of how much on-stack memory is too much
(a lot probably depends on the expected depth of the call stack too, and here it
doesn't appear to be too deep), but I see that
mlxsw_sp_bridge_vxlan_vlan_is_valid()
has a DECLARE_BITMAP(vlans, VLAN_N_VID) too.
The comment applies for callers of br_mst_get_info() too.
> + if (!seen)
> + return -ENOMEM;
> +
> + list_for_each_entry(v, &vg->vlan_list, vlist) {
> + if (test_bit(v->brvlan->msti, seen))
> + continue;
> +
> + nest = nla_nest_start_noflag(skb, IFLA_BRIDGE_MST_ENTRY);
> + if (!nest ||
> + nla_put_u16(skb, IFLA_BRIDGE_MST_ENTRY_MSTI,
> v->brvlan->msti) ||
> + nla_put_u8(skb, IFLA_BRIDGE_MST_ENTRY_STATE, v->state)) {
> + err = -EMSGSIZE;
> + break;
> + }
> + nla_nest_end(skb, nest);
> +
> + set_bit(v->brvlan->msti, seen);
> + }
> +
> + kfree(seen);
> + return err;
> +}
