Re: [patch net-next] net: sched: move block device tracking into tcf_block_get/put_ext()

Ido Schimmel
2024-01-10T12:10:01Z

On Thu, Jan 04, 2024 at 01:58:44PM +0100, Jiri Pirko wrote:
> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> index adf5de1ff773..253b26f2eddd 100644
> --- a/net/sched/cls_api.c
> +++ b/net/sched/cls_api.c
> @@ -1428,6 +1428,7 @@ int tcf_block_get_ext(struct tcf_block **p_block, struct Qdisc *q,
> struct tcf_block_ext_info *ei,
> struct netlink_ext_ack *extack)
> {
> + struct net_device *dev = qdisc_dev(q);
> struct net *net = qdisc_net(q);
> struct tcf_block *block = NULL;
> int err;
> @@ -1461,9 +1462,18 @@ int tcf_block_get_ext(struct tcf_block **p_block, struct Qdisc *q,
> if (err)
> goto err_block_offload_bind;
>
> + if (tcf_block_shared(block)) {
> + err = xa_insert(&block->ports, dev->ifindex, dev, GFP_KERNEL);
> + if (err) {
> + NL_SET_ERR_MSG(extack, "block dev insert failed");
> + goto err_dev_insert;
> + }
> + }

While this patch fixes the original issue, it creates another one:

# ip link add name swp1 type dummy
# tc qdisc replace dev swp1 root handle 10: prio bands 8 priomap 7 6 5 4 3 2 1
# tc qdisc add dev swp1 parent 10:8 handle 108: red limit 1000000 min 200000 max 200001 probability 1.0 avpkt 8000 burst 38 qevent early_drop block 10
RED: set bandwidth to 10Mbit
# tc qdisc add dev swp1 parent 10:7 handle 107: red limit 1000000 min 500000 max 500001 probability 1.0 avpkt 8000 burst 63 qevent early_drop block 10
RED: set bandwidth to 10Mbit
Error: block dev insert failed.

The reproducer does not fail if I revert this patch and apply Victor's
[1] instead.

[1] https://lore.kernel.org/netdev/20231231172320.245375-1-victor@mojatatu.com/

> +
> *p_block = block;
> return 0;
>
> +err_dev_insert:
> err_block_offload_bind:
> tcf_chain0_head_change_cb_del(block, ei);
> err_chain0_head_change_cb_add: