Re: [PATCH] lib/bitmap.c: return -EINVAL for grouping errors in __bitmap_parselist

[Pan Xinhui]

hi, Yury
	thanks for your nice reply.

On 2015å06æ29æ 21:39, Yury Norov wrote:
> > Sometimes the input from user may cause an unexpected result.
>
> Could you please provide specific example?
I wrote some scripts to do some tests about irqs.
echo "1-3," > /proc/irq/<xxx>/smp_affinity_list
this command ends with ',' by mistake.
actually __bitmap_parselist() will report "0-3" for the final result which is wrong.

> > just like __bitmap_parse, we return -EINVAL if there is no avaiable digit in each
> > parsing procedures.
> >
> > Signed-off-by: Pan Xinhui <xinhuix.pan@xxxxxxxxx>
>
> Hello, Pan.
>
> (Adding Alexey Klimov, Rasmus Villemoes)
>
> > ---
> >    lib/bitmap.c | 7 +++++--
> >    1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/bitmap.c b/lib/bitmap.c
> > index 64c0926..995fca2 100644
> > --- a/lib/bitmap.c
> > +++ b/lib/bitmap.c
> > @@ -504,7 +504,7 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen,
> >            int nmaskbits)
> >    {
> >        unsigned a, b;
> > -    int c, old_c, totaldigits;
> > +    int c, old_c, totaldigits, ndigits;
> >        const char __user __force *ubuf = (const char __user __force *)buf;
> >        int exp_digit, in_range;
> >
> > @@ -514,6 +514,7 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen,
> >            exp_digit = 1;
> >            in_range = 0;
> >            a = b = 0;
> > +        ndigits = 0;
> >
> >            /* Get the next cpu# or a range of cpu#'s */
> >            while (buflen) {
> > @@ -555,8 +556,10 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen,
> >                if (!in_range)
> >                    a = b;
> >                exp_digit = 0;
> > -            totaldigits++;
> > +            ndigits++; totaldigits++;
>
> I'm not happy with joining two statements to a single line.
> Maybe sometimes it's OK for loop iterators like
>
>      while (a[i][j]) {
>          i++; j++;
>      }
>
> But here it looks nasty. Anyway, it's minor.

thanks for pointing out my mistake about the code style :)

> >            }
> > +        if (ndigits == 0)
> > +            return -EINVAL;
>
> You can avoid in-loop incrementation of ndigits if you'll
> save current totaldigits to ndigits before loop, and check
> ndigits against totaldigits after the loop:
>
>      ndigits = totaldigits;
>      while (...) {
>           ...
>          totaldigits++;
>      }
>
>      if (ndigits == totaldigits)
>          return -EINVAL;
>
> Maybe it's a good point to rework initial __bitmap_parse() similar way...

your advice is a good idea, thanks.
I am also thinking if we can rewrite them into one function for common codes.

thanks for your reply again :)

thanks
xinhui

> >            if (!(a <= b))
> >                return -EINVAL;
> >            if (b >= nmaskbits)
> > --
> > 1.9.1
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