Re: [PATCH v2 1/2] platform/x86: Add new Dell UART backlight driver

[Andy Shevchenko <andy@kernel.org>]

On Mon, May 13, 2024 at 03:18:10PM +0200, Hans de Goede wrote:
> On 5/13/24 2:58 PM, Andy Shevchenko wrote:
> > On Mon, May 13, 2024 at 01:15:50PM +0200, Hans de Goede wrote:

...

> >> +static int dell_uart_bl_command(struct dell_uart_backlight *dell_bl,
> >> +				const u8 *cmd, int cmd_len,
> >> +				u8 *resp, int resp_max_len)
> >> +{
> >> +	int ret;
> >> +
> >> +	ret = mutex_lock_killable(&dell_bl->mutex);
> > 
> > Can't be called via cleanup.h?
> 
> I prefer to have the locking explicit rather then use cleanup.h .

Hmm... interesting, so you push-back the cleanup.h usage?

<snip>

> >> +		case RESP_CMD: /* CMD byte */
> >> +			if (dell_bl->resp[RESP_CMD] != dell_bl->pending_cmd) {
> >> +				dev_err(dell_bl->dev, "Response cmd 0x%02x != pending 0x%02x\n",
> >> +					dell_bl->resp[RESP_CMD], dell_bl->pending_cmd);
> >> +				dell_bl->status = -EIO;
> >> +				goto wakeup;
> >> +			}
> >> +			break;
> > 
> > No default case?
> 
> Nope, this checks the validity of the first 2 bytes / the header. The data is not checked.

Why not

		default:
			/* We do not check the data */
			break;

?

...

> >> +	dev_dbg(dev, "Firmware version: %.*s\n", resp[RESP_LEN] - 3, resp + RESP_DATA);
> > 
> > I would be on the safest side, i.e. not trusting that it will be NUL-terminated
> > string, hence something like %*pE?
> 
> Right, this is why the existing dev_dbg() already passes a precision and we do
> want to actually stop if there is a 0 there, which %pE does not do.

I'm talking about the opposite, when it might go over the boundary.

-- 
With Best Regards,
Andy Shevchenko