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-rw-r--r--include/linux/flex_array.h2
-rw-r--r--lib/flex_array.c51
2 files changed, 31 insertions, 22 deletions
diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h
index ebeb2f3ad068..6843cf193a44 100644
--- a/include/linux/flex_array.h
+++ b/include/linux/flex_array.h
@@ -21,6 +21,8 @@ struct flex_array {
struct {
int element_size;
int total_nr_elements;
+ int elems_per_part;
+ u32 reciprocal_elems;
struct flex_array_part *parts[];
};
/*
diff --git a/lib/flex_array.c b/lib/flex_array.c
index cab7621f98aa..9b8b89458c4c 100644
--- a/lib/flex_array.c
+++ b/lib/flex_array.c
@@ -24,6 +24,7 @@
#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/module.h>
+#include <linux/reciprocal_div.h>
struct flex_array_part {
char elements[FLEX_ARRAY_PART_SIZE];
@@ -70,15 +71,15 @@ static inline int elements_fit_in_base(struct flex_array *fa)
* Element size | Objects | Objects |
* PAGE_SIZE=4k | 32-bit | 64-bit |
* ---------------------------------|
- * 1 bytes | 4186112 | 2093056 |
- * 2 bytes | 2093056 | 1046528 |
- * 3 bytes | 1395030 | 697515 |
- * 4 bytes | 1046528 | 523264 |
- * 32 bytes | 130816 | 65408 |
- * 33 bytes | 126728 | 63364 |
- * 2048 bytes | 2044 | 1022 |
- * 2049 bytes | 1022 | 511 |
- * void * | 1046528 | 261632 |
+ * 1 bytes | 4177920 | 2088960 |
+ * 2 bytes | 2088960 | 1044480 |
+ * 3 bytes | 1392300 | 696150 |
+ * 4 bytes | 1044480 | 522240 |
+ * 32 bytes | 130560 | 65408 |
+ * 33 bytes | 126480 | 63240 |
+ * 2048 bytes | 2040 | 1020 |
+ * 2049 bytes | 1020 | 510 |
+ * void * | 1044480 | 261120 |
*
* Since 64-bit pointers are twice the size, we lose half the
* capacity in the base structure. Also note that no effort is made
@@ -88,11 +89,15 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total,
gfp_t flags)
{
struct flex_array *ret;
+ int elems_per_part = 0;
+ int reciprocal_elems = 0;
int max_size = 0;
- if (element_size)
- max_size = FLEX_ARRAY_NR_BASE_PTRS *
- FLEX_ARRAY_ELEMENTS_PER_PART(element_size);
+ if (element_size) {
+ elems_per_part = FLEX_ARRAY_ELEMENTS_PER_PART(element_size);
+ reciprocal_elems = reciprocal_value(elems_per_part);
+ max_size = FLEX_ARRAY_NR_BASE_PTRS * elems_per_part;
+ }
/* max_size will end up 0 if element_size > PAGE_SIZE */
if (total > max_size)
@@ -102,6 +107,8 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total,
return NULL;
ret->element_size = element_size;
ret->total_nr_elements = total;
+ ret->elems_per_part = elems_per_part;
+ ret->reciprocal_elems = reciprocal_elems;
if (elements_fit_in_base(ret) && !(flags & __GFP_ZERO))
memset(&ret->parts[0], FLEX_ARRAY_FREE,
FLEX_ARRAY_BASE_BYTES_LEFT);
@@ -112,7 +119,7 @@ EXPORT_SYMBOL(flex_array_alloc);
static int fa_element_to_part_nr(struct flex_array *fa,
unsigned int element_nr)
{
- return element_nr / FLEX_ARRAY_ELEMENTS_PER_PART(fa->element_size);
+ return reciprocal_divide(element_nr, fa->reciprocal_elems);
}
/**
@@ -141,12 +148,12 @@ void flex_array_free(struct flex_array *fa)
EXPORT_SYMBOL(flex_array_free);
static unsigned int index_inside_part(struct flex_array *fa,
- unsigned int element_nr)
+ unsigned int element_nr,
+ unsigned int part_nr)
{
unsigned int part_offset;
- part_offset = element_nr %
- FLEX_ARRAY_ELEMENTS_PER_PART(fa->element_size);
+ part_offset = element_nr - part_nr * fa->elems_per_part;
return part_offset * fa->element_size;
}
@@ -186,7 +193,7 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags)
int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
gfp_t flags)
{
- int part_nr;
+ int part_nr = 0;
struct flex_array_part *part;
void *dst;
@@ -202,7 +209,7 @@ int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
if (!part)
return -ENOMEM;
}
- dst = &part->elements[index_inside_part(fa, element_nr)];
+ dst = &part->elements[index_inside_part(fa, element_nr, part_nr)];
memcpy(dst, src, fa->element_size);
return 0;
}
@@ -217,7 +224,7 @@ EXPORT_SYMBOL(flex_array_put);
*/
int flex_array_clear(struct flex_array *fa, unsigned int element_nr)
{
- int part_nr;
+ int part_nr = 0;
struct flex_array_part *part;
void *dst;
@@ -233,7 +240,7 @@ int flex_array_clear(struct flex_array *fa, unsigned int element_nr)
if (!part)
return -EINVAL;
}
- dst = &part->elements[index_inside_part(fa, element_nr)];
+ dst = &part->elements[index_inside_part(fa, element_nr, part_nr)];
memset(dst, FLEX_ARRAY_FREE, fa->element_size);
return 0;
}
@@ -302,7 +309,7 @@ EXPORT_SYMBOL(flex_array_prealloc);
*/
void *flex_array_get(struct flex_array *fa, unsigned int element_nr)
{
- int part_nr;
+ int part_nr = 0;
struct flex_array_part *part;
if (!fa->element_size)
@@ -317,7 +324,7 @@ void *flex_array_get(struct flex_array *fa, unsigned int element_nr)
if (!part)
return NULL;
}
- return &part->elements[index_inside_part(fa, element_nr)];
+ return &part->elements[index_inside_part(fa, element_nr, part_nr)];
}
EXPORT_SYMBOL(flex_array_get);