Re: [PATCH v3 0/4] io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL

[Ming Lei <ming.lei@redhat.com>]

On Fri, Feb 20, 2026 at 07:55:33AM -0800, Caleb Sander Mateos wrote:
> On Fri, Feb 20, 2026 at 6:25 AM Ming Lei <ming.lei@redhat.com> wrote:
> >
> > On Thu, Feb 19, 2026 at 10:22:23AM -0700, Caleb Sander Mateos wrote:
> > > Currently, creating an io_uring with IORING_SETUP_IOPOLL requires all
> > > requests issued to it to support iopoll. This prevents, for example,
> > > using ublk zero-copy together with IORING_SETUP_IOPOLL, as ublk
> > > zero-copy buffer registrations are performed using a uring_cmd. There's
> > > no technical reason why these non-iopoll uring_cmds can't be supported.
> > > They will either complete synchronously or via an external mechanism
> > > that calls io_uring_cmd_done(), so they don't need to be polled.
> >
> > For sync uring command, it is fine to support for IOPOLL.
> >
> > However, there are async uring command, which may be completed in irq
> > context, or in multishot way, at least the later isn't supported in
> > io_do_iopoll() yet.
> 
> Can you describe the issues you envision in more detail?

Basically IOPOLL doesn't support multishot request yet.

For example, when io_uring_mshot_cmd_post_cqe() is called and new cqe is
queued, it can't be found from io_iopoll_check()<-io_uring_enter(IORING_ENTER_GETEVENTS).


Thanks,
Ming