On 9/26/22 20:40, Jens Axboe wrote:
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?
6.1 + stable sounds ok, I don't have an opinion on how to how
to merge it.
--
Pavel Begunkov
