Re: [PATCH v7 bpf-next 04/10] udp: seq_file: Remove bpf_seq_afinfo from udp_iter_state

From: Aditi Ghag <aditi.ghag@isovalent.com>
To: Aditi Ghag <aditi.ghag@isovalent.com>
Cc: bpf@vger.kernel.org, kafai@fb.com,
	Stanislav Fomichev <sdf@google.com>,
	Martin KaFai Lau <martin.lau@kernel.org>
Subject: Re: [PATCH v7 bpf-next 04/10] udp: seq_file: Remove bpf_seq_afinfo from udp_iter_state
Date: Wed, 3 May 2023 18:25:25 -0700	[thread overview]
Message-ID: <73779BBC-48BB-4FE9-A673-36EA3DD79068@isovalent.com> (raw)
In-Reply-To: <20230503225351.3700208-5-aditi.ghag@isovalent.com>

> On May 3, 2023, at 3:53 PM, Aditi Ghag <aditi.ghag@isovalent.com> wrote:
> 
> This is a preparatory commit to remove the field. The field was
> previously shared between proc fs and BPF UDP socket iterators. As the
> follow-up commits will decouple the implementation for the iterators,
> remove the field. As for BPF socket iterator, filtering of sockets is
> exepected to be done in BPF programs.
> 
> Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
> Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
> ---
> include/net/udp.h |  1 -
> net/ipv4/udp.c    | 25 +++++--------------------
> 2 files changed, 5 insertions(+), 21 deletions(-)
> 
> diff --git a/include/net/udp.h b/include/net/udp.h
> index de4b528522bb..5cad44318d71 100644
> --- a/include/net/udp.h
> +++ b/include/net/udp.h
> @@ -437,7 +437,6 @@ struct udp_seq_afinfo {
> struct udp_iter_state {
> 	struct seq_net_private  p;
> 	int			bucket;
> -	struct udp_seq_afinfo	*bpf_seq_afinfo;
> };
> 
> void *udp_seq_start(struct seq_file *seq, loff_t *pos);
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index c426ebafeb13..9f8c1554a9e4 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -2993,14 +2993,16 @@ static bool seq_sk_match(struct seq_file *seq, const struct sock *sk)
> 		net_eq(sock_net(sk), seq_file_net(seq)));
> }
> 
> +static const struct seq_operations bpf_iter_udp_seq_ops;

>> net/ipv4/udp.c:3001:36: warning: 'bpf_iter_udp_seq_ops' defined but not used [-Wunused-const-variable=]
   3001 | static const struct seq_operations bpf_iter_udp_seq_ops;
        |                                    ^~~~~~~~~~~~~~~~~~~~

This would have to be wrapped with ifdef too. 

> static struct udp_table *udp_get_table_seq(struct seq_file *seq,
> 					   struct net *net)
> {
> -	const struct udp_iter_state *state = seq->private;
> 	const struct udp_seq_afinfo *afinfo;
> 
> -	if (state->bpf_seq_afinfo)
> +#ifdef CONFIG_BPF_SYSCALL
> +	if (seq->op == &bpf_iter_udp_seq_ops)
> 		return net->ipv4.udp_table;
> +#endif
> 
> 	afinfo = pde_data(file_inode(seq->file));
> 	return afinfo->udp_table ? : net->ipv4.udp_table;
> @@ -3424,28 +3426,11 @@ DEFINE_BPF_ITER_FUNC(udp, struct bpf_iter_meta *meta,
> 
> static int bpf_iter_init_udp(void *priv_data, struct bpf_iter_aux_info *aux)
> {
> -	struct udp_iter_state *st = priv_data;
> -	struct udp_seq_afinfo *afinfo;
> -	int ret;
> -
> -	afinfo = kmalloc(sizeof(*afinfo), GFP_USER | __GFP_NOWARN);
> -	if (!afinfo)
> -		return -ENOMEM;
> -
> -	afinfo->family = AF_UNSPEC;
> -	afinfo->udp_table = NULL;
> -	st->bpf_seq_afinfo = afinfo;
> -	ret = bpf_iter_init_seq_net(priv_data, aux);
> -	if (ret)
> -		kfree(afinfo);
> -	return ret;
> +	return bpf_iter_init_seq_net(priv_data, aux);
> }
> 
> static void bpf_iter_fini_udp(void *priv_data)
> {
> -	struct udp_iter_state *st = priv_data;
> -
> -	kfree(st->bpf_seq_afinfo);
> 	bpf_iter_fini_seq_net(priv_data);
> }
> 
> -- 
> 2.34.1
> 