linux-kernel - Re: [PATCH] usb: class: usblp: replace conditional statement with min()

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Date:   Tue, 3 Aug 2021 07:13:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Pete Zaitcev <zaitcev@...hat.com>
Cc:     Salah Triki <salah.triki@...il.com>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: class: usblp: replace conditional statement with
 min()

On Mon, Aug 02, 2021 at 08:50:22PM -0500, Pete Zaitcev wrote:
> On Tue, 3 Aug 2021 01:28:06 +0100
> Salah Triki <salah.triki@...il.com> wrote:
> 
> > Replace conditional statement with min() in order to make code cleaner. Issue
> > found by coccinelle.
> 
> > +++ b/drivers/usb/class/usblp.c
> >  		request, !!dir, recip, value, index, len, retval);
> > -	return retval < 0 ? retval : 0;
> > +	return min(retval, 0);
> >  }
> 
> I'm very much against this change. The function min() is there
> for numeric values. But here we have a situation where we
> do one thing if there was an error, and another thing if
> there was no error.
> 
> This sort of abuse is exactly why blindly clicking heels
> whenever a tool tells you is not optimal.
> 
> If the objective is to shut the tool up, please consider
> the following instead:
> 
> diff --git a/drivers/usb/class/usblp.c b/drivers/usb/class/usblp.c
> index 9596e4279294..bbcbcf199fa9 100644
> --- a/drivers/usb/class/usblp.c
> +++ b/drivers/usb/class/usblp.c
> @@ -264,7 +264,9 @@ static int usblp_ctrl_msg(struct usblp *usblp, int request, int type, int dir, i
>         dev_dbg(&usblp->intf->dev,
>                 "usblp_control_msg: rq: 0x%02x dir: %d recip: %d value: %d idx: %d len: %#x result: %d\n",
>                 request, !!dir, recip, value, index, len, retval);
> -       return retval < 0 ? retval : 0;
> +       if (retval < 0)
> +               return retval;
> +       return 0;
>  }

I agree with Pete here, this is the "correct" fix for this, using min()
is not ok here.

thanks,

greg k-h