Re: [PATCH v3 2/2] auxdisplay: charlcd: Deduplicate simple_strtoul()

Andy Shevchenko
2019-07-08T13:35:40Z

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@linux.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?

> I am afraid that it might cause some
> regressions.
>
> For example, the following input is strange but it is valid:
>
> x0x10; new code would return (16, <orig_y>) instead of (10, <orig_y>)
> x010; new code would return (8, <orig_y>) instead of (10, <orig_y>)
>
> Best Regards,
> Petr

--
With Best Regards,
Andy Shevchenko