Re: [PATCH] io_uring: check file_slot early when accept use fix_file mode

[Hao Xu <haoxu@linux.alibaba.com>]

在 2021/9/7 下午11:37, Jens Axboe 写道:
> On 9/7/21 9:32 AM, Hao Xu wrote:
>> 在 2021/9/7 下午11:24, Jens Axboe 写道:
>>> On 9/7/21 9:16 AM, Hao Xu wrote:
>>>> check file_slot early in io_accept_prep() to avoid wasted effort in
>>>> failure cases.
>>>
>>> It's generally better to just let the failure cases deal with it instead
>>> of having checks in multiple places. This is a failure path, so we don't
>>> care about making it fail early. Optimizations should be for the hot path,
>>> which is not a malformed sqe.
>> I have a question here: if we do do_accept() and but fail in
>> io_install_fixed_file(), do we lose the conn_fd return by do_accept()
>> forever?
> 
> We do. The file is put and everything, so we're not leaking anything.
> But the actual connection is lost as the accept request failed.
Does that cause any problem, since from client's perspective, connection
is builded, and there is no way for the server to close it.
>