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

[Pavel Begunkov <asml.silence@gmail.com>]

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};
};

-- 
Pavel Begunkov