Re: [PATCHSET 0/4] Add support for shared io-wq backends

[Jens Axboe <axboe@kernel.dk>]

On 1/26/20 8:11 AM, Pavel Begunkov wrote:
> On 1/26/2020 4:51 AM, Daurnimator wrote:
>> On Fri, 24 Jan 2020 at 10:16, Jens Axboe <axboe@kernel.dk> wrote:
>>
>> I don't love the idea of some new type of magic user<>kernel
>> identifier. It would be nice if the id itself was e.g. a file
>> descriptor
>>
>> What if when creating an io_uring you could pass in an existing
>> io_uring file descriptor, and the new one would share the io-wq
>> backend?
>>
> Good idea! It can solve potential problems with jails, isolation, etc in
> the future.
> 
> May we need having other shared resources and want fine-grained control
> over them at some moment? It can prove helpful for the BPF plans.
> E.g.
> 
> io_uring_setup(share_io-wq=ring_fd1,
>                share_fds=ring_fd2,
>                share_ebpf=ring_fd3, ...);
> 
> If so, it's better to have more flexible API. E.g. as follows or a
> pointer to a struct with @size field.
> 
> struct io_shared_resource {
>     int type;
>     int fd;
> };
> 
> struct io_uring_params {
>     ...
>     struct io_shared_resource shared[];
> };
> 
> params = {
>     ...
>     .shared = {{ATTACH_IO_WQ, fd1}, ..., SANTINEL_ENTRY};
> };

I'm fine with changing/extending the sharing API, please send a
patch!

-- 
Jens Axboe