Commit e8f98f24 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: always wait for sqd exited when stopping SQPOLL thread 



We have a tiny race where io_put_sq_data() calls io_sq_thead_stop()
and finds the thread gone, but the thread has indeed not fully
exited or called complete() yet. Close it up by always having
io_sq_thread_stop() wait on completion of the exit event.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 5199328a

fs/io_uring.c

+8 −8
Original line number Diff line number Diff line
@@ -7079,11 +7079,8 @@ static void io_sq_thread_stop(struct io_sq_data *sqd) 
	if (test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state))

		return;

	down_write(&sqd->rw_lock);

	if (!sqd->thread) {

		up_write(&sqd->rw_lock);

		return;

	}

	set_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);

	if (sqd->thread)

		wake_up_process(sqd->thread);

	up_write(&sqd->rw_lock);

	wait_for_completion(&sqd->exited);
@@ -7849,9 +7846,9 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx, 


			ret = -EINVAL;

			if (cpu >= nr_cpu_ids)

				goto err;

				goto err_sqpoll;

			if (!cpu_online(cpu))

				goto err;

				goto err_sqpoll;



			sqd->sq_cpu = cpu;

		} else {
@@ -7862,7 +7859,7 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx, 
		tsk = create_io_thread(io_sq_thread, sqd, NUMA_NO_NODE);

		if (IS_ERR(tsk)) {

			ret = PTR_ERR(tsk);

			goto err;

			goto err_sqpoll;

		}



		sqd->thread = tsk;
@@ -7881,6 +7878,9 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx, 
err:

	io_sq_thread_finish(ctx);

	return ret;

err_sqpoll:

	complete(&ctx->sq_data->exited);

	goto err;

}



static inline void __io_unaccount_mem(struct user_struct *user,