On 25.10.2024 16:14:03, Ming Yu wrote:

Marc Kleine-Budde [off-list ref] 於 2024年10月24日 週四 下午11:34寫道：

quoted

On 24.10.2024 17:20:57, Marc Kleine-Budde wrote:

[...]

quoted

quoted

+   nct6694->cmd_buffer = devm_kcalloc(dev, CMD_PACKET_SZ,
+                                      sizeof(unsigned char), GFP_KERNEL);
+   if (!nct6694->cmd_buffer)
+           return -ENOMEM;
+   nct6694->rx_buffer = devm_kcalloc(dev, MAX_PACKET_SZ,
+                                     sizeof(unsigned char), GFP_KERNEL);
+   if (!nct6694->rx_buffer)
+           return -ENOMEM;
+   nct6694->tx_buffer = devm_kcalloc(dev, MAX_PACKET_SZ,
+                                     sizeof(unsigned char), GFP_KERNEL);
+   if (!nct6694->tx_buffer)
+           return -ENOMEM;
+   nct6694->int_buffer = devm_kcalloc(dev, MAX_PACKET_SZ,
+                                      sizeof(unsigned char), GFP_KERNEL);
+   if (!nct6694->int_buffer)
+           return -ENOMEM;
+
+   nct6694->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+   if (!nct6694->int_in_urb) {
+           dev_err(&udev->dev, "Failed to allocate INT-in urb!\n");
+           return -ENOMEM;
+   }
+
+   /* Bulk pipe maximum packet for each transaction */
+   bulk_pipe = usb_sndbulkpipe(udev, BULK_OUT_ENDPOINT);
+   nct6694->maxp = usb_maxpacket(udev, bulk_pipe);
+
+   mutex_init(&nct6694->access_lock);
+   nct6694->udev = udev;
+   nct6694->timeout = URB_TIMEOUT; /* Wait until urb complete */
+
+   INIT_LIST_HEAD(&nct6694->handler_list);
+   spin_lock_init(&nct6694->lock);
+
+   usb_fill_int_urb(nct6694->int_in_urb, udev, pipe,
+                    nct6694->int_buffer, maxp, usb_int_callback,
+                    nct6694, int_endpoint->bInterval);
+   ret = usb_submit_urb(nct6694->int_in_urb, GFP_KERNEL);
+   if (ret)
+           goto err_urb;
+
+   dev_set_drvdata(&udev->dev, nct6694);
+   usb_set_intfdata(iface, nct6694);
+
+   ret = mfd_add_hotplug_devices(&udev->dev, nct6694_dev,
+                                 ARRAY_SIZE(nct6694_dev));
+   if (ret) {
+           dev_err(&udev->dev, "Failed to add mfd's child device\n");
+           goto err_mfd;
+   }
+
+   nct6694->async_workqueue = alloc_ordered_workqueue("asyn_workqueue", 0);

Where is the async_workqueue used?

Sorry - it's used in the driver, which live in separate directories -
you can ignore this comment.

But then the question comes up, it looks racy to _first_ add the devices
and _then_ the workqueue.

Excuse me, I'm a bit confused. Is there anything I need to
improve on?

It looks racy to _first_ add the devices and _then_ the workqueue.

So the obvious solution is to allocate the worklist first and then add
the devices.

regards,
Marc

-- 
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