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-rw-r--r--lib/flex_array.c87
1 files changed, 60 insertions, 27 deletions
diff --git a/lib/flex_array.c b/lib/flex_array.c
index c0ea40ba208..9b8b89458c4 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
@@ -88,8 +89,15 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total,
gfp_t flags)
{
struct flex_array *ret;
- int max_size = FLEX_ARRAY_NR_BASE_PTRS *
- FLEX_ARRAY_ELEMENTS_PER_PART(element_size);
+ int elems_per_part = 0;
+ int reciprocal_elems = 0;
+ int max_size = 0;
+
+ 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)
@@ -99,6 +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);
@@ -109,7 +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);
}
/**
@@ -138,12 +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;
}
@@ -183,20 +193,23 @@ __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 = fa_element_to_part_nr(fa, element_nr);
+ int part_nr = 0;
struct flex_array_part *part;
void *dst;
if (element_nr >= fa->total_nr_elements)
return -ENOSPC;
+ if (!fa->element_size)
+ return 0;
if (elements_fit_in_base(fa))
part = (struct flex_array_part *)&fa->parts[0];
else {
+ part_nr = fa_element_to_part_nr(fa, element_nr);
part = __fa_get_part(fa, part_nr, flags);
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;
}
@@ -211,20 +224,23 @@ EXPORT_SYMBOL(flex_array_put);
*/
int flex_array_clear(struct flex_array *fa, unsigned int element_nr)
{
- int part_nr = fa_element_to_part_nr(fa, element_nr);
+ int part_nr = 0;
struct flex_array_part *part;
void *dst;
if (element_nr >= fa->total_nr_elements)
return -ENOSPC;
+ if (!fa->element_size)
+ return 0;
if (elements_fit_in_base(fa))
part = (struct flex_array_part *)&fa->parts[0];
else {
+ part_nr = fa_element_to_part_nr(fa, element_nr);
part = fa->parts[part_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;
}
@@ -232,10 +248,10 @@ EXPORT_SYMBOL(flex_array_clear);
/**
* flex_array_prealloc - guarantee that array space exists
- * @fa: the flex array for which to preallocate parts
- * @start: index of first array element for which space is allocated
- * @end: index of last (inclusive) element for which space is allocated
- * @flags: page allocation flags
+ * @fa: the flex array for which to preallocate parts
+ * @start: index of first array element for which space is allocated
+ * @nr_elements: number of elements for which space is allocated
+ * @flags: page allocation flags
*
* This will guarantee that no future calls to flex_array_put()
* will allocate memory. It can be used if you are expecting to
@@ -245,15 +261,27 @@ EXPORT_SYMBOL(flex_array_clear);
* Locking must be provided by the caller.
*/
int flex_array_prealloc(struct flex_array *fa, unsigned int start,
- unsigned int end, gfp_t flags)
+ unsigned int nr_elements, gfp_t flags)
{
int start_part;
int end_part;
int part_nr;
+ unsigned int end;
struct flex_array_part *part;
- if (start >= fa->total_nr_elements || end >= fa->total_nr_elements)
+ if (!start && !nr_elements)
+ return 0;
+ if (start >= fa->total_nr_elements)
return -ENOSPC;
+ if (!nr_elements)
+ return 0;
+
+ end = start + nr_elements - 1;
+
+ if (end >= fa->total_nr_elements)
+ return -ENOSPC;
+ if (!fa->element_size)
+ return 0;
if (elements_fit_in_base(fa))
return 0;
start_part = fa_element_to_part_nr(fa, start);
@@ -281,19 +309,22 @@ EXPORT_SYMBOL(flex_array_prealloc);
*/
void *flex_array_get(struct flex_array *fa, unsigned int element_nr)
{
- int part_nr = fa_element_to_part_nr(fa, element_nr);
+ int part_nr = 0;
struct flex_array_part *part;
+ if (!fa->element_size)
+ return NULL;
if (element_nr >= fa->total_nr_elements)
return NULL;
if (elements_fit_in_base(fa))
part = (struct flex_array_part *)&fa->parts[0];
else {
+ part_nr = fa_element_to_part_nr(fa, element_nr);
part = fa->parts[part_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);
@@ -343,6 +374,8 @@ int flex_array_shrink(struct flex_array *fa)
int part_nr;
int ret = 0;
+ if (!fa->total_nr_elements || !fa->element_size)
+ return 0;
if (elements_fit_in_base(fa))
return ret;
for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) {
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-03-30 20:22:46 +0000