io_uring: cancel more aggressively in exit_work

While io_ring_exit_work() is running new requests of all sorts may be
issued, so it should do a bit more to cancel them, otherwise they may
just get stuck. e.g. in io-wq, in poll lists, etc.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -992,6 +992,9 @@ enum io_mem_account {
 	ACCT_PINNED,
 };
 
+static void __io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
+					    struct task_struct *task);
+
 static void destroy_fixed_file_ref_node(struct fixed_file_ref_node *ref_node);
 static struct fixed_file_ref_node *alloc_fixed_file_ref_node(
 			struct io_ring_ctx *ctx);
@@ -8675,7 +8678,7 @@ static void io_ring_exit_work(struct work_struct *work)
 	 * as nobody else will be looking for them.
 	 */
 	do {
-		io_iopoll_try_reap_events(ctx);
+		__io_uring_cancel_task_requests(ctx, NULL);
 	} while (!wait_for_completion_timeout(&ctx->ref_comp, HZ/20));
 	io_ring_ctx_free(ctx);
 }
@@ -8830,9 +8833,11 @@ static void __io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
 		enum io_wq_cancel cret;
 		bool ret = false;
 
-		cret = io_wq_cancel_cb(ctx->io_wq, io_cancel_task_cb, &cancel, true);
-		if (cret != IO_WQ_CANCEL_NOTFOUND)
-			ret = true;
+		if (ctx->io_wq) {
+			cret = io_wq_cancel_cb(ctx->io_wq, io_cancel_task_cb,
+					       &cancel, true);
+			ret |= (cret != IO_WQ_CANCEL_NOTFOUND);
+		}
 
 		/* SQPOLL thread does its own polling */
 		if (!(ctx->flags & IORING_SETUP_SQPOLL)) {