mm/damon: move damon_rand() definition into damon.h

damon_rand() is called in three files:damon/core.c, damon/ paddr.c,
damon/vaddr.c, i think there is no need to redefine this twice, So move
it to damon.h will be a good choice.

Link: https://lkml.kernel.org/r/20211202075859.51341-1-xhao@linux.alibaba.com
Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/damon.h

@@ -11,12 +11,16 @@
 #include <linux/mutex.h>
 #include <linux/time64.h>
 #include <linux/types.h>
+#include <linux/random.h>
 
 /* Minimal region size.  Every damon_region is aligned by this. */
 #define DAMON_MIN_REGION	PAGE_SIZE
 /* Max priority score for DAMON-based operation schemes */
 #define DAMOS_MAX_SCORE		(99)
 
+/* Get a random number in [l, r) */
+#define damon_rand(l, r) (l + prandom_u32_max(r - l))
+
 /**
  * struct damon_addr_range - Represents an address region of [@start, @end).
  * @start:	Start address of the region (inclusive).

mm/damon/core.c

@@ -11,7 +11,6 @@
 #include <linux/delay.h>
 #include <linux/kthread.h>
 #include <linux/mm.h>
-#include <linux/random.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 
@@ -23,9 +22,6 @@
 #define DAMON_MIN_REGION 1
 #endif
 
-/* Get a random number in [l, r) */
-#define damon_rand(l, r) (l + prandom_u32_max(r - l))
-
 static DEFINE_MUTEX(damon_lock);
 static int nr_running_ctxs;
 

mm/damon/prmtv-common.h

@@ -6,10 +6,6 @@
  */
 
 #include <linux/damon.h>
-#include <linux/random.h>
-
-/* Get a random number in [l, r) */
-#define damon_rand(l, r) (l + prandom_u32_max(r - l))
 
 struct page *damon_get_page(unsigned long pfn);