/* * Flexible array managed in PAGE_SIZE parts * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * Copyright IBM Corporation, 2009 * * Author: Dave Hansen */ #include #include #include #include #include struct flex_array_part { char elements[FLEX_ARRAY_PART_SIZE]; }; static inline int elements_fit_in_base(struct flex_array *fa) { int data_size = fa->element_size * fa->total_nr_elements; if (data_size <= FLEX_ARRAY_BASE_BYTES_LEFT) return 1; return 0; } 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) { 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; } if (total > max_size) return NULL; ret = kzalloc(sizeof(struct flex_array), flags); if (!ret) 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); return ret; } EXPORT_SYMBOL(flex_array_alloc); static int fa_element_to_part_nr(struct flex_array *fa, unsigned int element_nr) { return reciprocal_divide(element_nr, fa->reciprocal_elems); } void flex_array_free_parts(struct flex_array *fa) { int part_nr; if (elements_fit_in_base(fa)) return; 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 part_nr) { unsigned int part_offset; part_offset = element_nr - part_nr * fa->elems_per_part; return part_offset * fa->element_size; } static struct flex_array_part * __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags) { struct flex_array_part *part = fa->parts[part_nr]; if (!part) { 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; } int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, gfp_t flags) { 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, part_nr)]; memcpy(dst, src, fa->element_size); return 0; } EXPORT_SYMBOL(flex_array_put); int flex_array_clear(struct flex_array *fa, unsigned int 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, part_nr)]; memset(dst, FLEX_ARRAY_FREE, fa->element_size); return 0; } EXPORT_SYMBOL(flex_array_clear); int flex_array_prealloc(struct flex_array *fa, unsigned int start, 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 && !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); end_part = fa_element_to_part_nr(fa, end); for (part_nr = start_part; part_nr <= end_part; part_nr++) { part = __fa_get_part(fa, part_nr, flags); if (!part) return -ENOMEM; } return 0; } EXPORT_SYMBOL(flex_array_prealloc); void *flex_array_get(struct flex_array *fa, unsigned int 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, part_nr)]; } EXPORT_SYMBOL(flex_array_get); 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) { int i; for (i = 0; i < sizeof(struct flex_array_part); i++) if (part->elements[i] != FLEX_ARRAY_FREE) return 0; return 1; } int flex_array_shrink(struct flex_array *fa) { struct flex_array_part *part; 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++) { part = fa->parts[part_nr]; if (!part) continue; if (part_is_free(part)) { fa->parts[part_nr] = NULL; kfree(part); ret++; } } return ret; } EXPORT_SYMBOL(flex_array_shrink);