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

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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






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