Re: [PATCH bpf-next v5 2/8] net: Update an existing TCP congestion control algorithm.

Kui-Feng Lee
2023-03-08T22:51:12Z

On 3/8/23 10:59, Martin KaFai Lau wrote:
> On 3/7/23 4:50 PM, Kui-Feng Lee wrote:
>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>> index 50cfc2388cbc..00b6e1a2edaf 100644
>> --- a/include/linux/bpf.h
>> +++ b/include/linux/bpf.h
>> @@ -1512,6 +1512,8 @@ struct bpf_struct_ops {
>>                  void *kdata, const void *udata);
>>       int (*reg)(void *kdata);
>>       void (*unreg)(void *kdata);
>> +    int (*update)(void *kdata, void *old_kdata);
>> +    int (*validate)(void *kdata);
>>       const struct btf_type *type;
>>       const struct btf_type *value_type;
>>       const char *name;
>> diff --git a/include/net/tcp.h b/include/net/tcp.h
>> index db9f828e9d1e..2abb755e6a3a 100644
>> --- a/include/net/tcp.h
>> +++ b/include/net/tcp.h
>> @@ -1117,6 +1117,9 @@ struct tcp_congestion_ops {
>>   int tcp_register_congestion_control(struct tcp_congestion_ops *type);
>>   void tcp_unregister_congestion_control(struct tcp_congestion_ops
>> *type);
>> +int tcp_update_congestion_control(struct tcp_congestion_ops *type,
>> +                  struct tcp_congestion_ops *old_type);
>> +int tcp_validate_congestion_control(struct tcp_congestion_ops *ca);
>>   void tcp_assign_congestion_control(struct sock *sk);
>>   void tcp_init_congestion_control(struct sock *sk);
>> diff --git a/net/bpf/bpf_dummy_struct_ops.c
>> b/net/bpf/bpf_dummy_struct_ops.c
>> index ff4f89a2b02a..158f14e240d0 100644
>> --- a/net/bpf/bpf_dummy_struct_ops.c
>> +++ b/net/bpf/bpf_dummy_struct_ops.c
>> @@ -222,12 +222,18 @@ static void bpf_dummy_unreg(void *kdata)
>>   {
>>   }
>> +static int bpf_dummy_update(void *kdata, void *old_kdata)
>> +{
>> +    return -EOPNOTSUPP;
>> +}
>> +
>>   struct bpf_struct_ops bpf_bpf_dummy_ops = {
>>       .verifier_ops = &bpf_dummy_verifier_ops,
>>       .init = bpf_dummy_init,
>>       .check_member = bpf_dummy_ops_check_member,
>>       .init_member = bpf_dummy_init_member,
>>       .reg = bpf_dummy_reg,
>> +    .update = bpf_dummy_update,
>>       .unreg = bpf_dummy_unreg,
>>       .name = "bpf_dummy_ops",
>>   };
>> diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
>> index 13fc0c185cd9..e8b27826283e 100644
>> --- a/net/ipv4/bpf_tcp_ca.c
>> +++ b/net/ipv4/bpf_tcp_ca.c
>> @@ -239,8 +239,6 @@ static int bpf_tcp_ca_init_member(const struct
>> btf_type *t,
>>           if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name,
>>                        sizeof(tcp_ca->name)) <= 0)
>>               return -EINVAL;
>> -        if (tcp_ca_find(utcp_ca->name))
>> -            return -EEXIST;
>
> This belongs to patch 3 where BPF_F_LINK needs this. move it closer to
> where it is actually used.

Got it!

>
>>           return 1;
>>       }
>> @@ -266,13 +264,25 @@ static void bpf_tcp_ca_unreg(void *kdata)
>>       tcp_unregister_congestion_control(kdata);
>>   }
>> +static int bpf_tcp_ca_update(void *kdata, void *old_kdata)
>> +{
>> +    return tcp_update_congestion_control(kdata, old_kdata);
>> +}
>> +
>> +static int bpf_tcp_ca_validate(void *kdata)
>> +{
>> +    return tcp_validate_congestion_control(kdata);
>> +}
>> +
>>   struct bpf_struct_ops bpf_tcp_congestion_ops = {
>>       .verifier_ops = &bpf_tcp_ca_verifier_ops,
>>       .reg = bpf_tcp_ca_reg,
>>       .unreg = bpf_tcp_ca_unreg,
>> +    .update = bpf_tcp_ca_update,
>>       .check_member = bpf_tcp_ca_check_member,
>>       .init_member = bpf_tcp_ca_init_member,
>>       .init = bpf_tcp_ca_init,
>> +    .validate = bpf_tcp_ca_validate,
>>       .name = "tcp_congestion_ops",
>>   };
>
> In general, please move "validate" related bpf changes to patch 3 and
> "update" related changes to patch 5. They are bpf specific (including
> the changes in bpf_tcp_ca.c) and closer to where it will be used.
>
> Then patch 2 should only have changes in tcp_cong.c as the preparation
> work for the later bpf needs. Please cc netdev for patch 2 in the next
> re-spin.
>
Sure