diff options
Diffstat (limited to 'lib/flex_array.c')
| -rw-r--r-- | lib/flex_array.c | 121 |
1 files changed, 90 insertions, 31 deletions
diff --git a/lib/flex_array.c b/lib/flex_array.c index 7baed2fc3bc8..66eef2e4483e 100644 --- a/lib/flex_array.c +++ b/lib/flex_array.c @@ -28,23 +28,6 @@ struct flex_array_part { char elements[FLEX_ARRAY_PART_SIZE]; }; -static inline int __elements_per_part(int element_size) -{ - return FLEX_ARRAY_PART_SIZE / element_size; -} - -static inline int bytes_left_in_base(void) -{ - int element_offset = offsetof(struct flex_array, parts); - int bytes_left = FLEX_ARRAY_BASE_SIZE - element_offset; - return bytes_left; -} - -static inline int nr_base_part_ptrs(void) -{ - return bytes_left_in_base() / sizeof(struct flex_array_part *); -} - /* * If a user requests an allocation which is small * enough, we may simply use the space in the @@ -54,7 +37,7 @@ static inline int nr_base_part_ptrs(void) static inline int elements_fit_in_base(struct flex_array *fa) { int data_size = fa->element_size * fa->total_nr_elements; - if (data_size <= bytes_left_in_base()) + if (data_size <= FLEX_ARRAY_BASE_BYTES_LEFT) return 1; return 0; } @@ -63,6 +46,7 @@ static inline int elements_fit_in_base(struct flex_array *fa) * flex_array_alloc - allocate a new flexible array * @element_size: the size of individual elements in the array * @total: total number of elements that this should hold + * @flags: page allocation flags to use for base array * * Note: all locking must be provided by the caller. * @@ -103,7 +87,8 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total, gfp_t flags) { struct flex_array *ret; - int max_size = nr_base_part_ptrs() * __elements_per_part(element_size); + int max_size = FLEX_ARRAY_NR_BASE_PTRS * + FLEX_ARRAY_ELEMENTS_PER_PART(element_size); /* max_size will end up 0 if element_size > PAGE_SIZE */ if (total > max_size) @@ -113,17 +98,21 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total, return NULL; ret->element_size = element_size; ret->total_nr_elements = total; + if (elements_fit_in_base(ret) && !(flags & __GFP_ZERO)) + memset(ret->parts[0], FLEX_ARRAY_FREE, + FLEX_ARRAY_BASE_BYTES_LEFT); return ret; } static int fa_element_to_part_nr(struct flex_array *fa, unsigned int element_nr) { - return element_nr / __elements_per_part(fa->element_size); + return element_nr / FLEX_ARRAY_ELEMENTS_PER_PART(fa->element_size); } /** * flex_array_free_parts - just free the second-level pages + * @fa: the flex array from which to free parts * * This is to be used in cases where the base 'struct flex_array' * has been statically allocated and should not be free. @@ -131,11 +120,10 @@ static int fa_element_to_part_nr(struct flex_array *fa, void flex_array_free_parts(struct flex_array *fa) { int part_nr; - int max_part = nr_base_part_ptrs(); if (elements_fit_in_base(fa)) return; - for (part_nr = 0; part_nr < max_part; part_nr++) + for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) kfree(fa->parts[part_nr]); } @@ -150,7 +138,8 @@ static unsigned int index_inside_part(struct flex_array *fa, { unsigned int part_offset; - part_offset = element_nr % __elements_per_part(fa->element_size); + part_offset = element_nr % + FLEX_ARRAY_ELEMENTS_PER_PART(fa->element_size); return part_offset * fa->element_size; } @@ -159,15 +148,12 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags) { struct flex_array_part *part = fa->parts[part_nr]; if (!part) { - /* - * This leaves the part pages uninitialized - * and with potentially random data, just - * as if the user had kmalloc()'d the whole. - * __GFP_ZERO can be used to zero it. - */ - part = kmalloc(FLEX_ARRAY_PART_SIZE, flags); + part = kmalloc(sizeof(struct flex_array_part), flags); if (!part) return NULL; + if (!(flags & __GFP_ZERO)) + memset(part, FLEX_ARRAY_FREE, + sizeof(struct flex_array_part)); fa->parts[part_nr] = part; } return part; @@ -175,9 +161,12 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags) /** * flex_array_put - copy data into the array at @element_nr - * @src: address of data to copy into the array + * @fa: the flex array to copy data into * @element_nr: index of the position in which to insert * the new element. + * @src: address of data to copy into the array + * @flags: page allocation flags to use for array expansion + * * * Note that this *copies* the contents of @src into * the array. If you are trying to store an array of @@ -207,9 +196,38 @@ int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, } /** + * flex_array_clear - clear element in array at @element_nr + * @fa: the flex array of the element. + * @element_nr: index of the position to clear. + * + * Locking must be provided by the caller. + */ +int flex_array_clear(struct flex_array *fa, unsigned int element_nr) +{ + int part_nr = fa_element_to_part_nr(fa, element_nr); + struct flex_array_part *part; + void *dst; + + if (element_nr >= fa->total_nr_elements) + return -ENOSPC; + if (elements_fit_in_base(fa)) + part = (struct flex_array_part *)&fa->parts[0]; + else { + part = fa->parts[part_nr]; + if (!part) + return -EINVAL; + } + dst = &part->elements[index_inside_part(fa, element_nr)]; + memset(dst, FLEX_ARRAY_FREE, fa->element_size); + return 0; +} + +/** * 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 * * This will guarantee that no future calls to flex_array_put() * will allocate memory. It can be used if you are expecting to @@ -242,6 +260,7 @@ int flex_array_prealloc(struct flex_array *fa, unsigned int start, /** * flex_array_get - pull data 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 a pointer to the data at index @element_nr. Note @@ -266,3 +285,43 @@ void *flex_array_get(struct flex_array *fa, unsigned int element_nr) } return &part->elements[index_inside_part(fa, element_nr)]; } + +static int part_is_free(struct flex_array_part *part) +{ + int i; + + for (i = 0; i < sizeof(struct flex_array_part); i++) + if (part->elements[i] != FLEX_ARRAY_FREE) + return 0; + return 1; +} + +/** + * flex_array_shrink - free unused second-level pages + * @fa: the flex array to shrink + * + * Frees all second-level pages that consist solely of unused + * elements. Returns the number of pages freed. + * + * Locking must be provided by the caller. + */ +int flex_array_shrink(struct flex_array *fa) +{ + struct flex_array_part *part; + int part_nr; + int ret = 0; + + if (elements_fit_in_base(fa)) + return ret; + for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) { + part = fa->parts[part_nr]; + if (!part) + continue; + if (part_is_free(part)) { + fa->parts[part_nr] = NULL; + kfree(part); + ret++; + } + } + return ret; +} |