2021-12-06 12:41:39

by haoxin

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

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 <[email protected]>
Signed-off-by: Xin Hao <[email protected]>
---
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);
+}

/**
* struct damon_addr_range - Represents an address region of [@start, @end).
--
2.31.0


2021-12-06 12:45:29

by SeongJae Park

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

On Mon, 6 Dec 2021 20:41:29 +0800 Xin Hao <[email protected]> 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 <[email protected]>
> Signed-off-by: Xin Hao <[email protected]>
> ---
> 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?


Thanks,
SJ

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

2021-12-06 12:48:23

by haoxin

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


On 12/6/21 8:45 PM, SeongJae Park wrote:
> On Mon, 6 Dec 2021 20:41:29 +0800 Xin Hao <[email protected]> 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 <[email protected]>
>> Signed-off-by: Xin Hao <[email protected]>
>> ---
>> 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