[PATCH 3/5] io_uring: consider ring dead once the ref is marked dying

Jens Axboe
2025-03-21T19:31:44Z

Don't gate this on the task exiting flag. It's generally not a good idea
to gate it on the task PF_EXITING flag anyway. Once the ring is starting
to go through ring teardown, the ref is marked as dying. Use that as
our fallback/cancel mechanism.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
io_uring/io_uring.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 2b9dae588f04..984db01f5184 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -555,7 +555,8 @@ static void io_queue_iowq(struct io_kiocb *req)
* procedure rather than attempt to run this request (or create a new
* worker for it).
*/
- if (WARN_ON_ONCE(!same_thread_group(tctx->task, current)))
+ if (WARN_ON_ONCE(!same_thread_group(tctx->task, current) &&
+ !percpu_ref_is_dying(&req->ctx->refs)))
atomic_or(IO_WQ_WORK_CANCEL, &req->work.flags);

trace_io_uring_queue_async_work(req, io_wq_is_hashed(&req->work));
@@ -1254,7 +1255,8 @@ static void io_req_normal_work_add(struct io_kiocb *req)
return;
}

- if (likely(!task_work_add(tctx->task, &tctx->task_work, ctx->notify_method)))
+ if (!percpu_ref_is_dying(&ctx->refs) &&
+ !task_work_add(tctx->task, &tctx->task_work, ctx->notify_method))
return;

io_fallback_tw(tctx, false);
--
2.49.0