linux-kernel - Re: [PATCH] vsprintf: Drop unused assignment of fmt.state

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Message-ID: <Z6oWaZl7DRoW0tDK@smile.fi.intel.com>
Date: Mon, 10 Feb 2025 17:08:25 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Petr Mladek <pmladek@...e.com>
Cc: I Hsin Cheng <richard120310@...il.com>, rostedt@...dmis.org,
	linux@...musvillemoes.dk, senozhatsky@...omium.org,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	jserv@...s.ncku.edu.tw, shuah@...nel.org
Subject: Re: [PATCH] vsprintf: Drop unused assignment of fmt.state

On Mon, Feb 10, 2025 at 02:09:53PM +0100, Petr Mladek wrote:
> On Thu 2025-02-06 17:32:32, Andy Shevchenko wrote:
> > On Thu, Feb 06, 2025 at 01:25:07AM +0800, I Hsin Cheng wrote:
> > > Remove unused assignment of "fmt.state", in both cases the value of
> > > "fmt.state" will be overwritten by either "FORMAT_STATE_PRECISION" or
> > > "FORMAT_STATE_NUM", the value "FORMAT_STATE_NONE" isn't going to be used
> > > after the assignment.

...

> > > struct fmt format_decode(struct fmt fmt, struct printf_spec *spec)
> > 
> > >  			spec->field_width = -spec->field_width;
> > >  			spec->flags |= LEFT;
> > >  		}
> > > -		fmt.state = FORMAT_STATE_NONE;
> > > +
> > >  		goto precision;
> > >  	}
> > >  
> > 
> > While both are kinda redundant, this is not obvious what's stated in the commit
> > message. Yes, `goto qualifier;` is straightforward, but not `goto precision;`.
> > Which makes me think that these assignments can make code robust against
> > potential future changes to allow to catch up the wrong code paths.
> 
> I fully agree with Andy here.
> 
> That said, I see the following right below the two conditions modified
> in this patch:
> 
> 	/* By default */
> 	fmt.state = FORMAT_STATE_NONE;
> 
> A good solution would be to move it up. It will be then obvious
> that we could remove these two initializations. I mean
> to do the following:

Which can't be performed (one need to check the old value first somehow) :-)

-- 
With Best Regards,
Andy Shevchenko