netdev - Re: [PATCH bpf-next 02/10] bpf: Implement BPF link handling for tc BPF programs

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Message-ID: <72deafd9-ebd0-e173-0b41-51820a317292@linux.dev>
Date:   Thu, 6 Oct 2022 10:56:32 -0700
From:   Martin KaFai Lau <martin.lau@...ux.dev>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     razor@...ckwall.org, ast@...nel.org, andrii@...nel.org,
        john.fastabend@...il.com, joannelkoong@...il.com, memxor@...il.com,
        toke@...hat.com, joe@...ium.io, netdev@...r.kernel.org,
        bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf-next 02/10] bpf: Implement BPF link handling for tc
 BPF programs

On 10/4/22 4:11 PM, Daniel Borkmann wrote:

> @@ -191,7 +202,8 @@ static void __xtc_prog_detach_all(struct net_device *dev, bool ingress, u32 limi
>   		if (!prog)
>   			break;
>   		dev_xtc_entry_prio_del(entry, item->bpf_priority);
> -		bpf_prog_put(prog);
> +		if (!item->bpf_id)
> +			bpf_prog_put(prog);

Should the link->dev be set to NULL somewhere?

>   		if (ingress)
>   			net_dec_ingress_queue();
>   		else
> @@ -244,6 +256,7 @@ __xtc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr,
>   		if (!prog)
>   			break;
>   		info.prog_id = prog->aux->id;
> +		info.link_id = item->bpf_id;
>   		info.prio = item->bpf_priority;
>   		if (copy_to_user(uinfo + i, &info, sizeof(info)))
>   			return -EFAULT;
> @@ -272,3 +285,90 @@ int xtc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
>   	rtnl_unlock();
>   	return ret;
>   }
> +

[ ... ]

> +static void xtc_link_release(struct bpf_link *l)
> +{
> +	struct bpf_tc_link *link = container_of(l, struct bpf_tc_link, link);
> +
> +	rtnl_lock();
> +	if (link->dev) {
> +		WARN_ON(__xtc_prog_detach(link->dev,
> +					  link->location == BPF_NET_INGRESS,
> +					  XTC_MAX_ENTRIES, l->id, link->priority));
> +		link->dev = NULL;
> +	}
> +	rtnl_unlock();
> +}