Re: [PATCH] gpib: lpvo_usb: rewrite DLE/STX sequence validation using !(A && B) for clarity

[Johan Hovold <johan@kernel.org>]

On Sat, May 16, 2026 at 11:12:27AM +0800, sunliming@web.codeaurora.org wrote:
> From: sunliming <sunliming@kylinos.cn>
> 
> Fix below smatch warnings:
> drivers/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c:808 usb_gpib_read() warn: was
> && intended here instead of ||?

This warning doesn't apply here where the two calls to one_char() return
different values.

It's meant to catch cases where the wrong operator is used so that a
condition is always true:

	(x != a || x != b) <=> !(x == a && x == b) <=> true	(a != b)

> Signed-off-by: sunliming <sunliming@kylinos.cn>
> ---
>  drivers/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c b/drivers/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c
> index e6ea9422d6f2..3e09f8226a56 100644
> --- a/drivers/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c
> +++ b/drivers/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c
> @@ -802,7 +802,7 @@ static int usb_gpib_read(struct gpib_board *board,
>  	if (retval < 0)
>  		goto read_return;
>  
> -	if (one_char(board, &b) != DLE || one_char(board, &b) != STX) {
> +	if (!(one_char(board, &b) == DLE && one_char(board, &b) == STX)) {

Whether one prefer one over the other here is just a matter of taste.

>  		dev_err(board->gpib_dev, "wrong <DLE><STX> sequence\n");
>  		retval = -EIO;
>  		goto read_return;

Johan