Re: [PATCH V1] mm/damon: Modify damon_rand() macro to static inline function

[Xin Hao]

On 12/6/21 8:45 PM, SeongJae Park wrote:
> On Mon, 6 Dec 2021 20:41:29 +0800 Xin Hao <xhao@xxxxxxxxxxxxxxxxx> wrote:
>
> > The damon_rand() func can not be implemented as a macro.
> > Example:
> > 	damon_rand(a++, b);
> > The value of 'a' will be incremented twice, This is obviously
> > unreasonable, So there fix it.
> >
> > Fixes: b9a6ac4e4ede ("mm/damon: adaptively adjust regions")
> > Reported-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
> > ---
> >   include/linux/damon.h | 5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/damon.h b/include/linux/damon.h
> > index c6df025d8704..bc9c8932b1e8 100644
> > --- a/include/linux/damon.h
> > +++ b/include/linux/damon.h
> > @@ -19,7 +19,10 @@
> >   #define DAMOS_MAX_SCORE		(99)
> >
> >   /* Get a random number in [l, r) */
> > -#define damon_rand(l, r) (l + prandom_u32_max(r - l))
> > +static inline unsigned long damon_rand(unsigned long l, unsigned long r)
> > +{
> > +	return l + (r - l);
> Seems prandom_u32_max() is missed?

Sorry, my fault, i write a simple test case like this, but i forgot to 
correct in patch, i will send a new one.

#include <stdio.h>

#define damon_rand(l, r) (l + (r - l))
static inline long damon_rand1(int l, int r)
{
        return l + (r - l);
}

int main(void)
{

        int a = 0;
        int b = 0;
        damon_rand(a++, 4);
        damon_rand1(b++, 4);

        printf("a is %d \n", a);
        printf("b is %d \n", b);

        return 0;
}

> Thanks,
> SJ
>
> > +}
> >
> >   /**
> >    * struct damon_addr_range - Represents an address region of [@start, @end).
> > --
> > 2.31.0

--
Best Regards!
Xin Hao