linux-kernel - Re: [PATCH v2] usb: raw-gadget: return -EINVAL if no proper ep address available

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Date:   Sun, 13 Mar 2022 15:52:35 +0100
From:   Andrey Konovalov <andreyknvl@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Wei Ming Chen <jj251510319013@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Felipe Balbi <balbi@...nel.org>,
        USB list <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v2] usb: raw-gadget: return -EINVAL if no proper ep
 address available

On Fri, Mar 11, 2022 at 9:30 AM Wei Ming Chen <jj251510319013@...il.com> wrote:
>
> If we try to use raw_ioctl_ep_enable() for ep5in on a hardware that
> only support from ep1-ep4 for both in and out direction, it will return
> -EBUSY originally.
>
> I think it will be more intuitive if we return -EINVAL, because -EBUSY
> sounds like ep5in is not available now, but might be available in the
> future.
>
> Signed-off-by: Wei Ming Chen <jj251510319013@...il.com>
> ---
>
> Changes in v2:
> - Rename variable from ep_num_matched to ep_props_matched
> - Incorporate the patch from Andrey Konovalov that cover
>   the foloowing cases:
>     1. If there are no endpoints that match the provided descriptor, return
>        EINVAL.
>     2. If there are matching endpoints, but they are all already enabled,
>        return EBUSY.
>
>  drivers/usb/gadget/legacy/raw_gadget.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/gadget/legacy/raw_gadget.c b/drivers/usb/gadget/legacy/raw_gadget.c
> index d86c3a36441e..e5707626c4d4 100644
> --- a/drivers/usb/gadget/legacy/raw_gadget.c
> +++ b/drivers/usb/gadget/legacy/raw_gadget.c
> @@ -758,6 +758,7 @@ static int raw_ioctl_ep_enable(struct raw_dev *dev, unsigned long value)
>         unsigned long flags;
>         struct usb_endpoint_descriptor *desc;
>         struct raw_ep *ep;
> +       bool ep_props_matched = false;
>
>         desc = memdup_user((void __user *)value, sizeof(*desc));
>         if (IS_ERR(desc))
> @@ -787,13 +788,14 @@ static int raw_ioctl_ep_enable(struct raw_dev *dev, unsigned long value)
>
>         for (i = 0; i < dev->eps_num; i++) {
>                 ep = &dev->eps[i];
> -               if (ep->state != STATE_EP_DISABLED)
> -                       continue;
>                 if (ep->addr != usb_endpoint_num(desc) &&
>                                 ep->addr != USB_RAW_EP_ADDR_ANY)
>                         continue;
>                 if (!usb_gadget_ep_match_desc(dev->gadget, ep->ep, desc, NULL))
>                         continue;
> +               ep_props_matched = true;
> +               if (ep->state != STATE_EP_DISABLED)
> +                       continue;
>                 ep->ep->desc = desc;
>                 ret = usb_ep_enable(ep->ep);
>                 if (ret < 0) {
> @@ -815,8 +817,13 @@ static int raw_ioctl_ep_enable(struct raw_dev *dev, unsigned long value)
>                 goto out_unlock;
>         }
>
> -       dev_dbg(&dev->gadget->dev, "fail, no gadget endpoints available\n");
> -       ret = -EBUSY;
> +       if (!ep_props_matched) {
> +               dev_dbg(&dev->gadget->dev, "fail, bad endpoint descriptor\n");
> +               ret = -EINVAL;
> +       } else {
> +               dev_dbg(&dev->gadget->dev, "fail, no endpoints available\n");
> +               ret = -EBUSY;
> +       }
>
>  out_free:
>         kfree(desc);
> --
> 2.25.1
>

Reviewed-by: Andrey Konovalov <andreyknvl@...il.com>

Greg, could you consider picking this up?

Thanks!