Re: [PATCH v2 1/2] io_uring/zcrx: add single shot recvzc

[David Wei <dw@davidwei.uk>]

On 2025-02-21 16:56, Pavel Begunkov wrote:
> On 2/21/25 20:51, David Wei wrote:
>> diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
>> index f2d326e18e67..74bca4e471bc 100644
>> --- a/io_uring/zcrx.c
>> +++ b/io_uring/zcrx.c
> ...
>>   static int io_zcrx_tcp_recvmsg(struct io_kiocb *req, struct io_zcrx_ifq *ifq,
>>                   struct sock *sk, int flags,
>> -                unsigned issue_flags)
>> +                unsigned issue_flags, unsigned int *outlen)
>>   {
>> +    unsigned int len = *outlen;
>> +    bool limit = len != UINT_MAX;
>>       struct io_zcrx_args args = {
>>           .req = req,
>>           .ifq = ifq,
>>           .sock = sk->sk_socket,
>>       };
>>       read_descriptor_t rd_desc = {
>> -        .count = 1,
>> +        .count = len,
>>           .arg.data = &args,
>>       };
>>       int ret;
>>         lock_sock(sk);
>>       ret = tcp_read_sock(sk, &rd_desc, io_zcrx_recv_skb);
>> +    if (limit && ret)
>> +        *outlen = len - ret;
> 
> ret can be negative, the check will pass and the calculations
> will turn it into something weird.
> 

:facepalm:

ret is an int and if (ret) is any non-zero value... I'll be more
explicit here to say ret > 0