On Thu, Mar 25, 2021 at 03:29:21PM +0300, Heikki Krogerus wrote:
> Introducing usb_for_each_port(). It works the same way as
> usb_for_each_dev(), but instead of going through every USB
> device in the system, it walks through the USB ports in the
> system.
>
> Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
This has a couple of nasty errors.
> ---
> drivers/usb/core/usb.c | 43 ++++++++++++++++++++++++++++++++++++++++++
> include/linux/usb.h | 1 +
> 2 files changed, 44 insertions(+)
>
> diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
> index 2ce3667ec6fae..6d49db9a1b208 100644
> --- a/drivers/usb/core/usb.c
> +++ b/drivers/usb/core/usb.c
> @@ -398,6 +398,49 @@ int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *))
> }
> EXPORT_SYMBOL_GPL(usb_for_each_dev);
>
> +struct each_hub_arg {
> + void *data;
> + int (*fn)(struct device *, void *);
> +};
> +
> +static int __each_hub(struct device *dev, void *data)
> +{
> + struct each_hub_arg *arg = (struct each_hub_arg *)data;
> + struct usb_device *hdev = to_usb_device(dev);
to_usb_device() won't work properly if the struct device isn't embedded
in an actual usb_device structure. And that will happen, since the USB
bus type holds usb_interface structures as well as usb_devices.
In fact, you should use usb_for_each_dev here; it already does what you
want.
> + struct usb_hub *hub;
> + int ret;
> + int i;
> +
> + hub = usb_hub_to_struct_hub(hdev);
> + if (!hub)
> + return 0;
> +
> + for (i = 0; i < hdev->maxchild; i++) {
> + ret = arg->fn(&hub->ports[i]->dev, arg->data);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
Don't you need some sort of locking or refcounting here? What would
happen if this hub got removed while the routine was running?
Alan Stern
