Re: [PATCH] x86/lib: Fix overflow of variable m when val >= 1410065408

[Colin King (gmail)]

On 02/11/2023 16:38, Dave Hansen wrote:
> On 11/1/23 08:32, Colin Ian King wrote:
> ...
> >   int num_digits(int val)
> >   {
> > -	int m = 10;
> > +	long m = 10;
> >   	int d = 1;
> >   
> >   	if (val < 0) {
>
> Isn't this still broken on 32-bit where sizeof(long) == sizeof(int)?
> Seems like we need 'm' to be able to hold values that are ~10x larger
> than 'val' if we need this to work for the entire int range.

Good point, long long is required for 32 bit,

sizes:
arch     int   long   long long
i386     4     4      8
x86_64   4     8      8

I'll send a V2.


> Also, performance doesn't matter here at *all* with the current use in
> a couple of printk()'s.  Just making 'm' 'long long' or u64 probably be
> just fine.