diff options
Diffstat (limited to 'lib/flex_array.c')
| -rw-r--r-- | lib/flex_array.c | 124 |
1 files changed, 95 insertions, 29 deletions
diff --git a/lib/flex_array.c b/lib/flex_array.c index 66eef2e4483e..6948a6692fc4 100644 --- a/lib/flex_array.c +++ b/lib/flex_array.c @@ -23,6 +23,8 @@ #include <linux/flex_array.h> #include <linux/slab.h> #include <linux/stddef.h> +#include <linux/export.h> +#include <linux/reciprocal_div.h> struct flex_array_part { char elements[FLEX_ARRAY_PART_SIZE]; @@ -69,15 +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 @@ -87,8 +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) @@ -98,16 +107,19 @@ 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, + memset(&ret->parts[0], FLEX_ARRAY_FREE, FLEX_ARRAY_BASE_BYTES_LEFT); return ret; } +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); } /** @@ -126,20 +138,22 @@ void flex_array_free_parts(struct flex_array *fa) for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) kfree(fa->parts[part_nr]); } +EXPORT_SYMBOL(flex_array_free_parts); void flex_array_free(struct flex_array *fa) { flex_array_free_parts(fa); kfree(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; } @@ -171,29 +185,35 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags) * Note that this *copies* the contents of @src into * the array. If you are trying to store an array of * pointers, make sure to pass in &ptr instead of ptr. + * You may instead wish to use the flex_array_put_ptr() + * helper function. * * Locking must be provided by the caller. */ 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; } +EXPORT_SYMBOL(flex_array_put); /** * flex_array_clear - clear element in array at @element_nr @@ -204,30 +224,34 @@ int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, */ 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; } +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 @@ -237,15 +261,27 @@ int flex_array_clear(struct flex_array *fa, unsigned int element_nr) * 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); @@ -257,6 +293,7 @@ int flex_array_prealloc(struct flex_array *fa, unsigned int start, } return 0; } +EXPORT_SYMBOL(flex_array_prealloc); /** * flex_array_get - pull data back out of the array @@ -265,26 +302,52 @@ int flex_array_prealloc(struct flex_array *fa, unsigned int start, * * Returns a pointer to the data at index @element_nr. Note * that this is a copy of the data that was passed in. If you - * are using this to store pointers, you'll get back &ptr. + * are using this to store pointers, you'll get back &ptr. You + * may instead wish to use the flex_array_get_ptr helper. * * Locking must be provided by the caller. */ 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); + +/** + * flex_array_get_ptr - pull a ptr back out of the array + * @fa: the flex array from which to extract data + * @element_nr: index of the element to fetch from the array + * + * Returns the pointer placed in the flex array at element_nr using + * flex_array_put_ptr(). This function should not be called if the + * element in question was not set using the _put_ptr() helper. + */ +void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr) +{ + void **tmp; + + tmp = flex_array_get(fa, element_nr); + if (!tmp) + return NULL; + + return *tmp; +} +EXPORT_SYMBOL(flex_array_get_ptr); static int part_is_free(struct flex_array_part *part) { @@ -311,6 +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++) { @@ -325,3 +390,4 @@ int flex_array_shrink(struct flex_array *fa) } return ret; } +EXPORT_SYMBOL(flex_array_shrink); |