linux-kernel - Re: [PATCH v3 2/2] auxdisplay: charlcd: Deduplicate simple

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Date:   Mon, 8 Jul 2019 15:56:26 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mans Rullgard <mans@...sr.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] auxdisplay: charlcd: Deduplicate simple_strtoul()

On Mon 2019-07-08 16:35:34, Andy Shevchenko wrote:
> On Mon, Jul 08, 2019 at 03:16:52PM +0200, Petr Mladek wrote:
> > On Thu 2019-07-04 14:55:32, Andy Shevchenko wrote:
> > > Like in the commit
> > >   8b2303de399f ("serial: core: Fix handling of options after MMIO address")
> > > we may use simple_strtoul() which in comparison to kstrtoul() can do conversion
> > > in-place without additional and unnecessary code to be written.
> > > 
> > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > > ---
> > > - no change since v2
> > >  drivers/auxdisplay/charlcd.c | 34 +++++++---------------------------
> > >  1 file changed, 7 insertions(+), 27 deletions(-)
> > > 
> > > diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
> > > index 92745efefb54..3858dc7a4154 100644
> > > --- a/drivers/auxdisplay/charlcd.c
> > > +++ b/drivers/auxdisplay/charlcd.c
> > > @@ -287,31 +287,6 @@ static int charlcd_init_display(struct charlcd *lcd)
> > >  	return 0;
> > >  }
> > >  
> > > -/*
> > > - * Parses an unsigned integer from a string, until a non-digit character
> > > - * is found. The empty string is not accepted. No overflow checks are done.
> > > - *
> > > - * Returns whether the parsing was successful. Only in that case
> > > - * the output parameters are written to.
> > > - *
> > > - * TODO: If the kernel adds an inplace version of kstrtoul(), this function
> > > - * could be easily replaced by that.
> > > - */
> > > -static bool parse_n(const char *s, unsigned long *res, const char **next_s)
> > > -{
> > > -	if (!isdigit(*s))
> > > -		return false;
> > > -
> > > -	*res = 0;
> > > -	while (isdigit(*s)) {
> > > -		*res = *res * 10 + (*s - '0');
> > > -		++s;
> > > -	}
> > > -
> > > -	*next_s = s;
> > > -	return true;
> > > -}
> > > -
> > >  /*
> > >   * Parses a movement command of the form "(.*);", where the group can be
> > >   * any number of subcommands of the form "(x|y)[0-9]+".
> > > @@ -336,6 +311,7 @@ static bool parse_xy(const char *s, unsigned long *x, unsigned long *y)
> > >  {
> > >  	unsigned long new_x = *x;
> > >  	unsigned long new_y = *y;
> > > +	char *p;
> > >  
> > >  	for (;;) {
> > >  		if (!*s)
> > > @@ -345,11 +321,15 @@ static bool parse_xy(const char *s, unsigned long *x, unsigned long *y)
> > >  			break;
> > >  
> > >  		if (*s == 'x') {
> > > -			if (!parse_n(s + 1, &new_x, &s))
> > > +			new_x = simple_strtoul(s + 1, &p, 10);
> > 
> > simple_strtoul() tries to detect the base even when it has been
> > explicitely specified. 
> 
> I can't see it from the code. Can you point out to this drastic bug that has to
> be fixed?

Grr, the base is detected only when it was not defined.

I am sorry for the noise. I probably have not woken up fully after
the weekend yet.

The patch looks fine then. Feel free to use:

Reviewed-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr