Re: [PATCH] io_uring/net: clear msg_controllen on partial sendmsg retry

[Jens Axboe <axboe@kernel.dk>]

On 6/20/23 1:56?AM, Stefan Metzmacher wrote:
> Hi Jens,
> 
>> If we have cmsg attached AND we transferred partial data at least, clear
>> msg_controllen on retry so we don't attempt to send that again.
>>
>> Cc: stable@vger.kernel.org # 5.10+
>> Fixes: cac9e4418f4c ("io_uring/net: save msghdr->msg_control for retries")
>> Reported-by: Stefan Metzmacher <metze@samba.org>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
>> ---
>>
>> diff --git a/io_uring/net.c b/io_uring/net.c
>> index 51b0f7fbb4f5..fe1c478c7dec 100644
>> --- a/io_uring/net.c
>> +++ b/io_uring/net.c
>> @@ -326,6 +326,7 @@ int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
>>           if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
>>               return io_setup_async_msg(req, kmsg, issue_flags);
>>           if (ret > 0 && io_net_retry(sock, flags)) {
>> +            kmsg->msg.msg_controllen = 0;
>>               sr->done_io += ret;
>>               req->flags |= REQ_F_PARTIAL_IO;
>>               return io_setup_async_msg(req, kmsg, issue_flags);
>>
> 
> Should we also set 'kmsg->msg.msg_control' to NULL?

We could, but I don't think it matters as we gate any checks on that
anyway. But in terms of completeness, may as well I suppose.

-- 
Jens Axboe