On Friday, September 10, 2021 5:19:58 PM CEST Fabio M. De Francesco wrote:
> On Monday, September 6, 2021 4:07:26 PM CEST Greg Kroah-Hartman wrote:
> > On Sun, Sep 05, 2021 at 12:00:47AM +0200, Fabio M. De Francesco wrote:
> > > Shorten the calls chain of rtw_read8/16/32() down to the actual reads.
> > > For this purpose unify the three usb_read8/16/32 into the new
> > > usb_read(); make the latter parameterizable with 'size'; embed most of
> > > the code of usbctrl_vendorreq() into usb_read() and use in it the new
> > > usb_control_msg_recv() API of USB Core.
> > >
> > > Suggested-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > > Co-developed-by: Pavel Skripkin <paskripkin@xxxxxxxxx>
> > > Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx>
> > > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx>
> > > ---
> > >
> > > [...]
> > >
> > > + while (++vendorreq_times <= MAX_USBCTRL_VENDORREQ_TIMES) {
> > > + status = usb_control_msg_recv(udev, 0,
> REALTEK_USB_VENQT_CMD_REQ,
> > > +
> REALTEK_USB_VENQT_READ, value,
> > > +
> REALTEK_USB_VENQT_CMD_IDX, io_buf,
> > > + size,
> RTW_USB_CONTROL_MSG_TIMEOUT,
> > > + GFP_KERNEL);
> > > + if (!status) { /* Success this control transfer. */
> >
> > Comments go on the next line.
> >
> > > + rtw_reset_continual_urb_error(dvobjpriv);
> > > + memcpy(data, io_buf, size);
> > > + } else { /* error cases */
> >
> > Again, next line for the comment.
> >
> > > + DBG_88E("reg 0x%x, usb %s %u fail, status:
> %d vendorreq_times:%d\n",
> > > + value, "read", size, status,
> vendorreq_times);
> >
> > These should be removed eventually...
> >
> > > +
> > > + if (status == (-ESHUTDOWN) || status == -
> ENODEV) {
> > > + adapt->bSurpriseRemoved = true;
> >
> > Odd, but ok...
>
> I'm not so sure that it is OK. Please correct me if I'm wrong...
>
> The calls chain from usb_control_msg_recv() seems to be the following:
>
> usb_control_msg_recv/send()
> -> usb_control_msg()
> -> usb_internal_control_msg()
> -> usb_start_wait_urb()
> -> usb_submit_urb()
>
> Each of the above functions could fail for different reasons and if so they
> return the errors up to the first caller into "status". I can find no lines
> of code where the above-mentioned functions set and return -ESHUTDOWN.
>
> Unless I'm missing something obvious, "status" is a non-shared variable.
The
> variables that are assigned with errors in all five of the above-mentioned
> functions are also local (non shared) variables.
>
> To summarize: how could "status" be assigned -ESHUTDOWN? Is any point in
the
> chain that value assigned by a concurrent thread to a shared variable and
> then returned up to the caller (i.e., usb_control_msg_recv())?
>
> Since the code has this "if (status == (-ESHUTDOWN) || ...)" it expects
that
> sometimes it could be 'true', so I'm 100% sure that I can't see where my
> argument is not valid... :(
Sorry, please disregard my previous message.
I found that, somewhere about a couple of function deeper in the chain, the
-ESHUTDOWN error code can indeed be returned. I had to read again and again
every line of the chain until I saw that.
Fabio
> Can someone please help me to understand this topic?
>
> Thanks,
>
> Fabio
>
>
>
> >
> > > [...]
>
>
>
>
