diff options
| -rw-r--r-- | Documentation/core-api/flexible-arrays.rst | 130 | ||||
| -rw-r--r-- | Documentation/flexible-arrays.txt | 123 | ||||
| -rw-r--r-- | include/linux/flex_array.h | 149 | ||||
| -rw-r--r-- | include/linux/poison.h | 3 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/flex_array.c | 398 | ||||
| -rw-r--r-- | tools/include/linux/poison.h | 3 |
7 files changed, 1 insertions, 807 deletions
diff --git a/Documentation/core-api/flexible-arrays.rst b/Documentation/core-api/flexible-arrays.rst deleted file mode 100644 index b6b85a1b518e..000000000000 --- a/Documentation/core-api/flexible-arrays.rst +++ /dev/null @@ -1,130 +0,0 @@ - -=================================== -Using flexible arrays in the kernel -=================================== - -Large contiguous memory allocations can be unreliable in the Linux kernel. -Kernel programmers will sometimes respond to this problem by allocating -pages with :c:func:`vmalloc()`. This solution not ideal, though. On 32-bit -systems, memory from vmalloc() must be mapped into a relatively small address -space; it's easy to run out. On SMP systems, the page table changes required -by vmalloc() allocations can require expensive cross-processor interrupts on -all CPUs. And, on all systems, use of space in the vmalloc() range increases -pressure on the translation lookaside buffer (TLB), reducing the performance -of the system. - -In many cases, the need for memory from vmalloc() can be eliminated by piecing -together an array from smaller parts; the flexible array library exists to make -this task easier. - -A flexible array holds an arbitrary (within limits) number of fixed-sized -objects, accessed via an integer index. Sparse arrays are handled -reasonably well. Only single-page allocations are made, so memory -allocation failures should be relatively rare. The down sides are that the -arrays cannot be indexed directly, individual object size cannot exceed the -system page size, and putting data into a flexible array requires a copy -operation. It's also worth noting that flexible arrays do no internal -locking at all; if concurrent access to an array is possible, then the -caller must arrange for appropriate mutual exclusion. - -The creation of a flexible array is done with :c:func:`flex_array_alloc()`:: - - #include <linux/flex_array.h> - - struct flex_array *flex_array_alloc(int element_size, - unsigned int total, - gfp_t flags); - -The individual object size is provided by ``element_size``, while total is the -maximum number of objects which can be stored in the array. The flags -argument is passed directly to the internal memory allocation calls. With -the current code, using flags to ask for high memory is likely to lead to -notably unpleasant side effects. - -It is also possible to define flexible arrays at compile time with:: - - DEFINE_FLEX_ARRAY(name, element_size, total); - -This macro will result in a definition of an array with the given name; the -element size and total will be checked for validity at compile time. - -Storing data into a flexible array is accomplished with a call to -:c:func:`flex_array_put()`:: - - int flex_array_put(struct flex_array *array, unsigned int element_nr, - void *src, gfp_t flags); - -This call will copy the data from src into the array, in the position -indicated by ``element_nr`` (which must be less than the maximum specified when -the array was created). If any memory allocations must be performed, flags -will be used. The return value is zero on success, a negative error code -otherwise. - -There might possibly be a need to store data into a flexible array while -running in some sort of atomic context; in this situation, sleeping in the -memory allocator would be a bad thing. That can be avoided by using -``GFP_ATOMIC`` for the flags value, but, often, there is a better way. The -trick is to ensure that any needed memory allocations are done before -entering atomic context, using :c:func:`flex_array_prealloc()`:: - - int flex_array_prealloc(struct flex_array *array, unsigned int start, - unsigned int nr_elements, gfp_t flags); - -This function will ensure that memory for the elements indexed in the range -defined by ``start`` and ``nr_elements`` has been allocated. Thereafter, a -``flex_array_put()`` call on an element in that range is guaranteed not to -block. - -Getting data back out of the array is done with :c:func:`flex_array_get()`:: - - void *flex_array_get(struct flex_array *fa, unsigned int element_nr); - -The return value is a pointer to the data element, or NULL if that -particular element has never been allocated. - -Note that it is possible to get back a valid pointer for an element which -has never been stored in the array. Memory for array elements is allocated -one page at a time; a single allocation could provide memory for several -adjacent elements. Flexible array elements are normally initialized to the -value ``FLEX_ARRAY_FREE`` (defined as 0x6c in <linux/poison.h>), so errors -involving that number probably result from use of unstored array entries. -Note that, if array elements are allocated with ``__GFP_ZERO``, they will be -initialized to zero and this poisoning will not happen. - -Individual elements in the array can be cleared with -:c:func:`flex_array_clear()`:: - - int flex_array_clear(struct flex_array *array, unsigned int element_nr); - -This function will set the given element to ``FLEX_ARRAY_FREE`` and return -zero. If storage for the indicated element is not allocated for the array, -``flex_array_clear()`` will return ``-EINVAL`` instead. Note that clearing an -element does not release the storage associated with it; to reduce the -allocated size of an array, call :c:func:`flex_array_shrink()`:: - - int flex_array_shrink(struct flex_array *array); - -The return value will be the number of pages of memory actually freed. -This function works by scanning the array for pages containing nothing but -``FLEX_ARRAY_FREE`` bytes, so (1) it can be expensive, and (2) it will not work -if the array's pages are allocated with ``__GFP_ZERO``. - -It is possible to remove all elements of an array with a call to -:c:func:`flex_array_free_parts()`:: - - void flex_array_free_parts(struct flex_array *array); - -This call frees all elements, but leaves the array itself in place. -Freeing the entire array is done with :c:func:`flex_array_free()`:: - - void flex_array_free(struct flex_array *array); - -As of this writing, there are no users of flexible arrays in the mainline -kernel. The functions described here are also not exported to modules; -that will probably be fixed when somebody comes up with a need for it. - - -Flexible array functions ------------------------- - -.. kernel-doc:: include/linux/flex_array.h diff --git a/Documentation/flexible-arrays.txt b/Documentation/flexible-arrays.txt deleted file mode 100644 index a0f2989dd804..000000000000 --- a/Documentation/flexible-arrays.txt +++ /dev/null @@ -1,123 +0,0 @@ -=================================== -Using flexible arrays in the kernel -=================================== - -:Updated: Last updated for 2.6.32 -:Author: Jonathan Corbet <corbet@lwn.net> - -Large contiguous memory allocations can be unreliable in the Linux kernel. -Kernel programmers will sometimes respond to this problem by allocating -pages with vmalloc(). This solution not ideal, though. On 32-bit systems, -memory from vmalloc() must be mapped into a relatively small address space; -it's easy to run out. On SMP systems, the page table changes required by -vmalloc() allocations can require expensive cross-processor interrupts on -all CPUs. And, on all systems, use of space in the vmalloc() range -increases pressure on the translation lookaside buffer (TLB), reducing the -performance of the system. - -In many cases, the need for memory from vmalloc() can be eliminated by -piecing together an array from smaller parts; the flexible array library -exists to make this task easier. - -A flexible array holds an arbitrary (within limits) number of fixed-sized -objects, accessed via an integer index. Sparse arrays are handled -reasonably well. Only single-page allocations are made, so memory -allocation failures should be relatively rare. The down sides are that the -arrays cannot be indexed directly, individual object size cannot exceed the -system page size, and putting data into a flexible array requires a copy -operation. It's also worth noting that flexible arrays do no internal -locking at all; if concurrent access to an array is possible, then the -caller must arrange for appropriate mutual exclusion. - -The creation of a flexible array is done with:: - - #include <linux/flex_array.h> - - struct flex_array *flex_array_alloc(int element_size, - unsigned int total, - gfp_t flags); - -The individual object size is provided by element_size, while total is the -maximum number of objects which can be stored in the array. The flags -argument is passed directly to the internal memory allocation calls. With -the current code, using flags to ask for high memory is likely to lead to -notably unpleasant side effects. - -It is also possible to define flexible arrays at compile time with:: - - DEFINE_FLEX_ARRAY(name, element_size, total); - -This macro will result in a definition of an array with the given name; the -element size and total will be checked for validity at compile time. - -Storing data into a flexible array is accomplished with a call to:: - - int flex_array_put(struct flex_array *array, unsigned int element_nr, - void *src, gfp_t flags); - -This call will copy the data from src into the array, in the position -indicated by element_nr (which must be less than the maximum specified when -the array was created). If any memory allocations must be performed, flags -will be used. The return value is zero on success, a negative error code -otherwise. - -There might possibly be a need to store data into a flexible array while -running in some sort of atomic context; in this situation, sleeping in the -memory allocator would be a bad thing. That can be avoided by using -GFP_ATOMIC for the flags value, but, often, there is a better way. The -trick is to ensure that any needed memory allocations are done before -entering atomic context, using:: - - int flex_array_prealloc(struct flex_array *array, unsigned int start, - unsigned int nr_elements, gfp_t flags); - -This function will ensure that memory for the elements indexed in the range -defined by start and nr_elements has been allocated. Thereafter, a -flex_array_put() call on an element in that range is guaranteed not to -block. - -Getting data back out of the array is done with:: - - void *flex_array_get(struct flex_array *fa, unsigned int element_nr); - -The return value is a pointer to the data element, or NULL if that -particular element has never been allocated. - -Note that it is possible to get back a valid pointer for an element which -has never been stored in the array. Memory for array elements is allocated -one page at a time; a single allocation could provide memory for several -adjacent elements. Flexible array elements are normally initialized to the -value FLEX_ARRAY_FREE (defined as 0x6c in <linux/poison.h>), so errors -involving that number probably result from use of unstored array entries. -Note that, if array elements are allocated with __GFP_ZERO, they will be -initialized to zero and this poisoning will not happen. - -Individual elements in the array can be cleared with:: - - int flex_array_clear(struct flex_array *array, unsigned int element_nr); - -This function will set the given element to FLEX_ARRAY_FREE and return -zero. If storage for the indicated element is not allocated for the array, -flex_array_clear() will return -EINVAL instead. Note that clearing an -element does not release the storage associated with it; to reduce the -allocated size of an array, call:: - - int flex_array_shrink(struct flex_array *array); - -The return value will be the number of pages of memory actually freed. -This function works by scanning the array for pages containing nothing but -FLEX_ARRAY_FREE bytes, so (1) it can be expensive, and (2) it will not work -if the array's pages are allocated with __GFP_ZERO. - -It is possible to remove all elements of an array with a call to:: - - void flex_array_free_parts(struct flex_array *array); - -This call frees all elements, but leaves the array itself in place. -Freeing the entire array is done with:: - - void flex_array_free(struct flex_array *array); - -As of this writing, there are no users of flexible arrays in the mainline -kernel. The functions described here are also not exported to modules; -that will probably be fixed when somebody comes up with a need for it. diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h deleted file mode 100644 index b94fa61b51fb..000000000000 --- a/include/linux/flex_array.h +++ /dev/null @@ -1,149 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -#ifndef _FLEX_ARRAY_H -#define _FLEX_ARRAY_H - -#include <linux/types.h> -#include <linux/reciprocal_div.h> -#include <asm/page.h> - -#define FLEX_ARRAY_PART_SIZE PAGE_SIZE -#define FLEX_ARRAY_BASE_SIZE PAGE_SIZE - -struct flex_array_part; - -/* - * This is meant to replace cases where an array-like - * structure has gotten too big to fit into kmalloc() - * and the developer is getting tempted to use - * vmalloc(). - */ - -struct flex_array { - union { - struct { - int element_size; - int total_nr_elements; - int elems_per_part; - struct reciprocal_value reciprocal_elems; - struct flex_array_part *parts[]; - }; - /* - * This little trick makes sure that - * sizeof(flex_array) == PAGE_SIZE - */ - char padding[FLEX_ARRAY_BASE_SIZE]; - }; -}; - -/* Number of bytes left in base struct flex_array, excluding metadata */ -#define FLEX_ARRAY_BASE_BYTES_LEFT \ - (FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts)) - -/* Number of pointers in base to struct flex_array_part pages */ -#define FLEX_ARRAY_NR_BASE_PTRS \ - (FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *)) - -/* Number of elements of size that fit in struct flex_array_part */ -#define FLEX_ARRAY_ELEMENTS_PER_PART(size) \ - (FLEX_ARRAY_PART_SIZE / size) - -/* - * Defines a statically allocated flex array and ensures its parameters are - * valid. - */ -#define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total) \ - struct flex_array __arrayname = { { { \ - .element_size = (__element_size), \ - .total_nr_elements = (__total), \ - } } }; \ - static inline void __arrayname##_invalid_parameter(void) \ - { \ - BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS * \ - FLEX_ARRAY_ELEMENTS_PER_PART(__element_size)); \ - } - -/** - * flex_array_alloc() - Creates a flexible array. - * @element_size: individual object size. - * @total: maximum number of objects which can be stored. - * @flags: GFP flags - * - * Return: Returns an object of structure flex_array. - */ -struct flex_array *flex_array_alloc(int element_size, unsigned int total, - gfp_t flags); - -/** - * flex_array_prealloc() - Ensures that memory for the elements indexed in the - * range defined by start and nr_elements has been allocated. - * @fa: array to allocate memory to. - * @start: start address - * @nr_elements: number of elements to be allocated. - * @flags: GFP flags - * - */ -int flex_array_prealloc(struct flex_array *fa, unsigned int start, - unsigned int nr_elements, gfp_t flags); - -/** - * flex_array_free() - Removes all elements of a flexible array. - * @fa: array to be freed. - */ -void flex_array_free(struct flex_array *fa); - -/** - * flex_array_free_parts() - Removes all elements of a flexible array, but - * leaves the array itself in place. - * @fa: array to be emptied. - */ -void flex_array_free_parts(struct flex_array *fa); - -/** - * flex_array_put() - Stores data into a flexible array. - * @fa: array where element is to be stored. - * @element_nr: position to copy, must be less than the maximum specified when - * the array was created. - * @src: data source to be copied into the array. - * @flags: GFP flags - * - * Return: Returns zero on success, a negative error code otherwise. - */ -int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, - gfp_t flags); - -/** - * flex_array_clear() - Clears an individual element in the array, sets the - * given element to FLEX_ARRAY_FREE. - * @element_nr: element position to clear. - * @fa: array to which element to be cleared belongs. - * - * Return: Returns zero on success, -EINVAL otherwise. - */ -int flex_array_clear(struct flex_array *fa, unsigned int element_nr); - -/** - * flex_array_get() - Retrieves data into a flexible array. - * - * @element_nr: Element position to retrieve data from. - * @fa: array from which data is to be retrieved. - * - * Return: Returns a pointer to the data element, or NULL if that - * particular element has never been allocated. - */ -void *flex_array_get(struct flex_array *fa, unsigned int element_nr); - -/** - * flex_array_shrink() - Reduces the allocated size of an array. - * @fa: array to shrink. - * - * Return: Returns number of pages of memory actually freed. - * - */ -int flex_array_shrink(struct flex_array *fa); - -#define flex_array_put_ptr(fa, nr, src, gfp) \ - flex_array_put(fa, nr, (void *)&(src), gfp) - -void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr); - -#endif /* _FLEX_ARRAY_H */ diff --git a/include/linux/poison.h b/include/linux/poison.h index 5046bad0c1c5..d6d980a681c7 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -83,9 +83,6 @@ #define MUTEX_DEBUG_FREE 0x22 #define MUTEX_POISON_WW_CTX ((void *) 0x500 + POISON_POINTER_DELTA) -/********** lib/flex_array.c **********/ -#define FLEX_ARRAY_FREE 0x6c /* for use-after-free poisoning */ - /********** security/ **********/ #define KEY_DESTROY 0xbd diff --git a/lib/Makefile b/lib/Makefile index b798b41d01ae..4e066120a0d6 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -35,7 +35,7 @@ obj-y += lockref.o obj-y += bcd.o div64.o sort.o parser.o debug_locks.o random32.o \ bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \ - gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \ + gcd.o lcm.o list_sort.o uuid.o iov_iter.o clz_ctz.o \ bsearch.o find_bit.o llist.o memweight.o kfifo.o \ percpu-refcount.o rhashtable.o reciprocal_div.o \ once.o refcount.o usercopy.o errseq.o bucket_locks.o \ diff --git a/lib/flex_array.c b/lib/flex_array.c deleted file mode 100644 index 2eed22fa507c..000000000000 --- a/lib/flex_array.c +++ /dev/null @@ -1,398 +0,0 @@ -/* - * 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 <dave@linux.vnet.ibm.com> - */ - -#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]; -}; - -/* - * If a user requests an allocation which is small - * enough, we may simply use the space in the - * flex_array->parts[] array to store the user - * data. - */ -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; -} - -/** - * 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. - * - * @total is used to size internal structures. If the user ever - * accesses any array indexes >=@total, it will produce errors. - * - * The maximum number of elements is defined as: the number of - * elements that can be stored in a page times the number of - * page pointers that we can fit in the base structure or (using - * integer math): - * - * (PAGE_SIZE/element_size) * (PAGE_SIZE-8)/sizeof(void *) - * - * Here's a table showing example capacities. Note that the maximum - * index that the get/put() functions is just nr_objects-1. This - * basically means that you get 4MB of storage on 32-bit and 2MB on - * 64-bit. - * - * - * Element size | Objects | Objects | - * PAGE_SIZE=4k | 32-bit | 64-bit | - * ---------------------------------| - * 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 - * to efficiently pack objects across page boundaries. - */ -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 max_size = 0; - struct reciprocal_value reciprocal_elems = { 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) - 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) -{ - /* - * if element_size == 0 we don't get here, so we never touch - * the zeroed fa->reciprocal_elems, which would yield invalid - * results - */ - return reciprocal_divide(element_nr, fa->reciprocal_elems); -} - -/** - * 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. - */ -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; -} - -/** - * flex_array_put - copy data into the array at @element_nr - * @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 - * 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 = 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); - -/** - * 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 = 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); - -/** - * 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 - * @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 - * be holding a lock or in some atomic context while writing - * data into the array. - * - * Locking must be provided by the caller. - */ -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); - -/** - * 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 - * 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. 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 = 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); - -/** - * 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) -{ - 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 (!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); diff --git a/tools/include/linux/poison.h b/tools/include/linux/poison.h index 9fdcd3eaac3b..d29725769107 100644 --- a/tools/include/linux/poison.h +++ b/tools/include/linux/poison.h @@ -87,9 +87,6 @@ #define MUTEX_DEBUG_INIT 0x11 #define MUTEX_DEBUG_FREE 0x22 -/********** lib/flex_array.c **********/ -#define FLEX_ARRAY_FREE 0x6c /* for use-after-free poisoning */ - /********** security/ **********/ #define KEY_DESTROY 0xbd |