Re: [PATCH v3 2/3] staging: r8188eu: Shorten calls chain of rtw_read8/16/32()

[Pavel Skripkin]

On 9/6/21 5:07 PM, 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>
> > ---
> >
> > v2->v3: No changes.
> >
> > v1->v2: No changes.
> >
> >  drivers/staging/r8188eu/hal/usb_ops_linux.c | 92 +++++++++++++++++----
> >  1 file changed, 78 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/staging/r8188eu/hal/usb_ops_linux.c b/drivers/staging/r8188eu/hal/usb_ops_linux.c
> > index a87b0d2e87d0..f9c4fd5a2c53 100644
> > --- a/drivers/staging/r8188eu/hal/usb_ops_linux.c
> > +++ b/drivers/staging/r8188eu/hal/usb_ops_linux.c
> > @@ -97,38 +97,102 @@ static int usbctrl_vendorreq(struct intf_hdl *pintfhdl, u16 value, void *pdata,
> >  	return status;
> >  }
> >  
> > +static int usb_read(struct intf_hdl *intfhdl, u32 addr, void *data, u8 size)
> > +{
> > +	u16 value = (u16)(addr & 0x0000ffff);
>
> Why not just pass in the address as a 16bit value?
>
>
> > +	struct adapter *adapt = intfhdl->padapter;
> > +	struct dvobj_priv *dvobjpriv = adapter_to_dvobj(adapt);
> > +	struct usb_device *udev = dvobjpriv->pusbdev;
> > +	int status;
> > +	u8 *io_buf;
> > +	int vendorreq_times = 0;
> > +
> > +	if (adapt->bSurpriseRemoved || adapt->pwrctrlpriv.pnp_bstop_trx) {
> > +		status = -EPERM;
> > +		goto exit;
>
> This is "interesting" to see if it's really even working as they think
> it does, but let's leave it alone for now...
>
> > +	}
> > +
> > +	mutex_lock(&dvobjpriv->usb_vendor_req_mutex);
> > +
> > +	/*  Acquire IO memory for vendorreq */
> > +	io_buf = dvobjpriv->usb_vendor_req_buf;
> > +
> > +	if (!io_buf) {
> > +		DBG_88E("[%s] io_buf == NULL\n", __func__);
>
> How can this buffer ever be NULL?
>
> > +		status = -ENOMEM;
> > +		goto release_mutex;
> > +	}
>
> Why share a buffer at all anyway?
>
> > +	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...
>
> > +			} else {
> > +				struct hal_data_8188e *haldata = GET_HAL_DATA(adapt);
> > +
> > +				haldata->srestpriv.wifi_error_status = USB_VEN_REQ_CMD_FAIL;
>
> Why are we not saying the command failed even if the device was removed?
>
> But if we do say an error happened, why are we trying to send this out
> again?  What would happen to make it work the second time?
>
> > +			}
> > +
> > +			if (rtw_inc_and_chk_continual_urb_error(dvobjpriv)) {
> > +				adapt->bSurpriseRemoved = true;
>
> So we try to see if the device was removed again?
>
> > +				break;
> > +			}
> > +		}
> > +
> > +		/*  firmware download is checksummed, don't retry */
> > +		if ((value >= FW_8188E_START_ADDRESS && value <= FW_8188E_END_ADDRESS) || !status)
> > +			break;
>
> Nothing like a special case for firmware magic.
>
> Those calls should just use a different write function entirely,
> eventually, to remove this...
>
> Ok, I know you are just moving code around, this is fine, just pointing
> out things that should be fixed up eventually...

I agree with all statements, and I've asked maintainers about some of 
them before. It's 100% should be fixed, but we (me and Fabio) want to 
fix them step by step to not rebase every time new clean up goes in.

Our plan is: (Fabio, please, correct me, if I am wrong here)

1. ops removal + shorten call chain (this patch series)
2. my error handling series [1]
3. Clean ups for rtw_* functions (old usb_*)
4. Remove dead proc code + introduce new sysfs interface, based on old 
proc code.


We can prepare them all at once, but, IMO:

1. It will be really hard to review
2. A lot of rebasing through new versions, since there are a lot
clean ups appear every day.


I believe, our step-by-step plan should be more comfortable for all of us :)


Thank you!


[1] 
https://lore.kernel.org/linux-staging/cover.1629479152.git.paskripkin@xxxxxxxxx/



With regards,
Pavel Skripkin