Re: [PATCH v3 4/6] staging: r8188eu: add error handling of rtw_read16

Pavel Skripkin
2021-08-25T08:22:22Z

On 8/25/21 7:35 AM, Fabio M. De Francesco wrote:
> On Tuesday, August 24, 2021 9:27:35 AM CEST Pavel Skripkin wrote:
>> _rtw_read16 function can fail in case of usb transfer failure. But
>> previous function prototype wasn't designed to return an error to
>> caller. It can cause a lot uninit value bugs all across the driver code,
>> since rtw_read16() returns local stack variable to caller.
>>
>> Fix it by changing the prototype of this function. Now it returns an
>> int: 0 on success, negative error value on failure and callers should pass
>> the pointer to storage location for register value.
>>
>> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
>>
>> [...]
>>
>> -static u16 usb_read16(struct intf_hdl *pintfhdl, u32 addr)
>> +static int usb_read16(struct intf_hdl *pintfhdl, u32 addr, u16 *data)
>> {
>> u8 requesttype;
>> u16 wvalue;
>> u16 len;
>> - __le32 data;
>> + int res;
>> + __le32 tmp;
>> +
>> + if (WARN_ON(unlikely(!data)))
>> + return -EINVAL;
>>
>> requesttype = 0x01;/* read_in */
>> wvalue = (u16)(addr & 0x0000ffff);
>> len = 2;
>> - usbctrl_vendorreq(pintfhdl, wvalue, &data, len, requesttype);
>> + res = usbctrl_vendorreq(pintfhdl, wvalue, &tmp, len, requesttype);
>> + if (res < 0) {
>> + dev_err(dvobj_to_dev(pintfhdl->pintf_dev), "Failed to read 16 bytes: %d\n", res);
>> + return res;
>> + } else if (res != len) {
>
> Dear Pavel,
>
> Please note that if and when my patch "Use usb_control_msg_recv / send () in
> usbctrl_vendorreq ()" will be merged, "if (res! = len)" will always evaluate 'true'
> and usb_read16 () will always return -EIO even if usbctrl_vendorreq () succeeds.
>

Yep, thank you, but it depends on which series will go in first :)

There is a chance, that you will need to clean up this part, if mine
will be merged before yours

With regards,
Pavel Skripkin