Re: [PATCH v3 3/4] mptcp: build ADD_ADDR/echo-ADD_ADDR option according pm.add_signal

[Yonglong Li <liyonglong@chinatelecom.cn>]

On 2021/6/18 8:25, Mat Martineau wrote:
> 
> This goto isn't quite right. It jumps below with opts and remaining already modified, and may end up modifying 'remaining' again.
> 
> Would be better to separate the logic for sending echo-vs-signal, so the goto isn't necessary.

Thanks for your review. The goto logic is not right indeed. I will separate the logic for sending echo-vs-signal

> 
>> +        else if (remaining < len)
>> +            goto out;
>> +        remaining -= len;
>> +        *size += len;
>> +        opts->remote = remote;
>> +        flags = (u8)~BIT(MPTCP_ADD_ADDR_ECHO);
>> +        opts->suboptions |= OPTION_MPTCP_ADD_ECHO;
>> +        pr_debug("addr_id=%d, echo=1, port=%d addr_signal:%x",
>> +             opts->remote.id, ntohs(opts->remote.port), add_addr);
>> +    } else if (mptcp_pm_should_add_signal_addr(msk)) {
>> +add_addr:
>> +        if ((local.family == AF_INET6 || local.port) && skb &&
>> +            skb_is_tcp_pure_ack(skb)) {
>> +            pr_debug("drop other suboptions");
>> +            opts->suboptions = 0;
>> +            opts->ext_copy.use_ack = 0;
>> +            opts->ext_copy.use_map = 0;
>> +            remaining += opt_size;
>> +            drop_other_suboptions = true;
>> +        }
>> +        len = mptcp_add_addr_len(local.family, false, !!local.port);
>> +        if (remaining < len)
>> +            goto out;
>> +        *size += len;
>> +        opts->addr = local;
>>         opts->ahmac = add_addr_generate_hmac(msk->local_key,
>>                              msk->remote_key,
>>                              &opts->addr);
>> +        opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
>> +        flags = (u8)~BIT(MPTCP_ADD_ADDR_SIGNAL);
>> +        pr_debug("addr_id=%d, ahmac=%llu, echo=0, port=%d, addr_signal:%x",
>> +             opts->addr.id, opts->ahmac, ntohs(opts->addr.port), add_addr);
>>     }
>> -    pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d",
>> -         opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port));
>>
>> -    return true;
>> +    if (drop_other_suboptions)
>> +        *size -= opt_size;
>> +    spin_lock_bh(&msk->pm.lock);
>> +    WRITE_ONCE(msk->pm.addr_signal, flags | msk->pm.addr_signal);
>> +    spin_unlock_bh(&msk->pm.lock);
> 
> This would set bits in msk->pm.addr_signal rather than clear them. Did you intend '&' instead of '|'?

Sorry for this mistake. :(