RE: [PATCH net] wifi: rtw88: properly drop usb interface reference on error

[Ping-Ke Shih]

Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> If an error happens in the usb probe path, in rtw_usb_intf_init(), the
> usb interface reference needs to be properly dropped, otherwise is is
> incorrectly increased when returning to the USB core.
> 
> Cc: Ping-Ke Shih <pkshih@xxxxxxxxxxx>
> Cc: stable <stable@xxxxxxxxxx>
> Assisted-by: gkh_clanker_2000
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/net/wireless/realtek/rtw88/usb.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
> index 433b06c8d8a6..36ac20039ce2 100644
> --- a/drivers/net/wireless/realtek/rtw88/usb.c
> +++ b/drivers/net/wireless/realtek/rtw88/usb.c
> @@ -1046,13 +1046,17 @@ static int rtw_usb_intf_init(struct rtw_dev *rtwdev,
> 
>         rtwusb->udev = udev;
>         ret = rtw_usb_parse(rtwdev, intf);
> -       if (ret)
> +       if (ret) {
> +               usb_put_dev(udev);
>                 return ret;
> +       }
> 
>         rtwusb->usb_data = kcalloc(RTW_USB_MAX_RXTX_COUNT, sizeof(u32),
>                                    GFP_KERNEL);
> -       if (!rtwusb->usb_data)
> +       if (!rtwusb->usb_data) {
> +               usb_put_dev(udev);
>                 return -ENOMEM;
> +       }
> 
>         usb_set_intfdata(intf, rtwdev->hw);
> 

Since rtwusb->udev isn't used right after assignment in this function.
Would it be simpler that moving usb_get_dev() downward like below?

diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
index db60e142268d..6e5c9c6f3e00 100644
--- a/drivers/net/wireless/realtek/rtw88/usb.c
+++ b/drivers/net/wireless/realtek/rtw88/usb.c
@@ -1041,10 +1041,8 @@ static int rtw_usb_intf_init(struct rtw_dev *rtwdev,
                             struct usb_interface *intf)
 {
        struct rtw_usb *rtwusb = rtw_get_usb_priv(rtwdev);
-       struct usb_device *udev = usb_get_dev(interface_to_usbdev(intf));
        int ret;

-       rtwusb->udev = udev;
        ret = rtw_usb_parse(rtwdev, intf);
        if (ret)
                return ret;
@@ -1054,6 +1052,8 @@ static int rtw_usb_intf_init(struct rtw_dev *rtwdev,
        if (!rtwusb->usb_data)
                return -ENOMEM;

+       rtwusb->udev = usb_get_dev(interface_to_usbdev(intf));
+
        usb_set_intfdata(intf, rtwdev->hw);

        SET_IEEE80211_DEV(rtwdev->hw, &intf->dev);