diff options
Diffstat (limited to 'lib/flex_array.c')
| -rw-r--r-- | lib/flex_array.c | 65 |
1 files changed, 43 insertions, 22 deletions
diff --git a/lib/flex_array.c b/lib/flex_array.c index 854b57bd7d9d..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 @@ -88,8 +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; } @@ -264,6 +280,8 @@ int flex_array_prealloc(struct flex_array *fa, unsigned int start, 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); @@ -291,19 +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); @@ -353,7 +374,7 @@ int flex_array_shrink(struct flex_array *fa) int part_nr; int ret = 0; - if (!fa->total_nr_elements) + if (!fa->total_nr_elements || !fa->element_size) return 0; if (elements_fit_in_base(fa)) return ret; |