io_uring: iopoll requests should also wake task ->in_idle state

If we're freeing/finishing iopoll requests, ensure we check if the task
is in idling in terms of cancelation. Otherwise we could end up waiting
forever in __io_uring_task_cancel() if the task has active iopoll
requests that need cancelation.

Cc: stable@vger.kernel.org # 5.9+
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -2270,6 +2270,8 @@ static void io_req_free_batch_finish(struct io_ring_ctx *ctx,
 		struct io_uring_task *tctx = rb->task->io_uring;
 
 		percpu_counter_sub(&tctx->inflight, rb->task_refs);
+		if (atomic_read(&tctx->in_idle))
+			wake_up(&tctx->wait);
 		put_task_struct_many(rb->task, rb->task_refs);
 		rb->task = NULL;
 	}
@@ -2288,6 +2290,8 @@ static void io_req_free_batch(struct req_batch *rb, struct io_kiocb *req)
 			struct io_uring_task *tctx = rb->task->io_uring;
 
 			percpu_counter_sub(&tctx->inflight, rb->task_refs);
+			if (atomic_read(&tctx->in_idle))
+				wake_up(&tctx->wait);
 			put_task_struct_many(rb->task, rb->task_refs);
 		}
 		rb->task = req->task;