Re: [Linux-kernel-mentees] [PATCH 3/4] net: usb: rtl8150: use usb_control_msg_recv() and usb_control_msg_send()

[Himadri Pandya <himadrispandya@gmail.com>]

On Wed, Sep 23, 2020 at 3:52 PM Oliver Neukum <oneukum@suse.com> wrote:
>
> Am Mittwoch, den 23.09.2020, 14:35 +0530 schrieb Himadri Pandya:
>
> Hi,
>
> > Many usage of usb_control_msg() do not have proper error check on return
> > value leaving scope for bugs on short reads. New usb_control_msg_recv()
> > and usb_control_msg_send() nicely wraps usb_control_msg() with proper
> > error check. Hence use the wrappers instead of calling usb_control_msg()
> > directly.
> >
> > Signed-off-by: Himadri Pandya <himadrispandya@gmail.com>
> Nacked-by: Oliver Neukum <oneukum@suse.com>
>
> > ---
> >  drivers/net/usb/rtl8150.c | 32 ++++++--------------------------
> >  1 file changed, 6 insertions(+), 26 deletions(-)
> >
> > diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c
> > index 733f120c852b..e3002b675921 100644
> > --- a/drivers/net/usb/rtl8150.c
> > +++ b/drivers/net/usb/rtl8150.c
> > @@ -152,36 +152,16 @@ static const char driver_name [] = "rtl8150";
> >  */
> >  static int get_registers(rtl8150_t * dev, u16 indx, u16 size, void *data)
> >  {
> > -     void *buf;
> > -     int ret;
> > -
> > -     buf = kmalloc(size, GFP_NOIO);
>
> GFP_NOIO is used here for a reason. You need to use this helper
> while in contexts of error recovery and runtime PM.
>

Understood. Apologies for proposing such a stupid change.

> > -     if (!buf)
> > -             return -ENOMEM;
> > -
> > -     ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
> > -                           RTL8150_REQ_GET_REGS, RTL8150_REQT_READ,
> > -                           indx, 0, buf, size, 500);
> > -     if (ret > 0 && ret <= size)
> > -             memcpy(data, buf, ret);
> > -     kfree(buf);
> > -     return ret;
> > +     return usb_control_msg_recv(dev->udev, 0, RTL8150_REQ_GET_REGS,
> > +                                 RTL8150_REQT_READ, indx, 0, data,
> > +                                 size, 500);
>
> This internally uses kmemdup() with GFP_KERNEL.
> You cannot make this change. The API does not support it.
> I am afraid we will have to change the API first, before more
> such changes are done.
>
> I would suggest dropping the whole series for now.

Okay. Thanks for the review.

Regards,
Himadri

>
>         Regards
>                 Oliver
>
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