On 9/26/22 1:12 PM, Pavel Begunkov wrote:
> On 9/26/22 18:09, Dylan Yudaken wrote:
>> Instead of picking the task from the first submitter task, rather use the
>> creator task or in the case of disabled (IORING_SETUP_R_DISABLED) the
>> enabling task.
>>
>> This approach allows a lot of simplification of the logic here. This
>> removes init logic from the submission path, which can always be a bit
>> confusing, but also removes the need for locking to write (or read) the
>> submitter_task.
>>
>> Users that want to move a ring before submitting can create the ring
>> disabled and then enable it on the submitting task.
>
> I think Dylan briefly mentioned before that it might be a good
> idea to task limit registration as well. I can't think of a use
> case at the moment but I agree we may find some in the future.
>
>
> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> index 242d896c00f3..60a471e43fd9 100644
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -3706,6 +3706,9 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
> if (WARN_ON_ONCE(percpu_ref_is_dying(&ctx->refs)))
> return -ENXIO;
>
> + if (ctx->submitter_task && ctx->submitter_task != current)
> + return -EEXIST;
> +
> if (ctx->restricted) {
> if (opcode >= IORING_REGISTER_LAST)
> return -EINVAL;
Yes, I don't see any reason why not to enforce this for registration
too. Don't think there's currently a need to do so, but it'd be easy
to miss once we do add that. Let's queue that up for 6.1?
--
Jens Axboe
