flex_array: introduce DEFINE_FLEX_ARRAY
FLEX_ARRAY_INIT(element_size, total_nr_elements) cannot determine if either parameter is valid, so flex arrays which are statically allocated with this interface can easily become corrupted or reference beyond its allocated memory. This removes FLEX_ARRAY_INIT() as a struct flex_array initializer since no initializer may perform the required checking. Instead, the array is now defined with a new interface: DEFINE_FLEX_ARRAY(name, element_size, total_nr_elements) This may be prefixed with `static' for file scope. This interface includes compile-time checking of the parameters to ensure they are valid. Since the validity of both element_size and total_nr_elements depend on FLEX_ARRAY_BASE_SIZE and FLEX_ARRAY_PART_SIZE, the kernel build will fail if either of these predefined values changes such that the array parameters are no longer valid. Since BUILD_BUG_ON() requires compile time constants, several of the static inline functions that were once local to lib/flex_array.c had to be moved to include/linux/flex_array.h. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
4af5a2f770
commit
45b588d6e5
2 changed files with 36 additions and 30 deletions
|
@ -31,10 +31,32 @@ struct flex_array {
|
|||
};
|
||||
};
|
||||
|
||||
#define FLEX_ARRAY_INIT(size, total) { { {\
|
||||
.element_size = (size), \
|
||||
.total_nr_elements = (total), \
|
||||
} } }
|
||||
/* 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)); \
|
||||
}
|
||||
|
||||
struct flex_array *flex_array_alloc(int element_size, unsigned int total,
|
||||
gfp_t flags);
|
||||
|
|
|
@ -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;
|
||||
}
|
||||
|
@ -103,7 +86,8 @@ 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)
|
||||
|
@ -114,14 +98,15 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total,
|
|||
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, bytes_left_in_base());
|
||||
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);
|
||||
}
|
||||
|
||||
/**
|
||||
|
@ -133,11 +118,10 @@ 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]);
|
||||
}
|
||||
|
||||
|
@ -152,7 +136,8 @@ 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;
|
||||
}
|
||||
|
||||
|
@ -313,13 +298,12 @@ static int part_is_free(struct flex_array_part *part)
|
|||
int flex_array_shrink(struct flex_array *fa)
|
||||
{
|
||||
struct flex_array_part *part;
|
||||
int max_part = nr_base_part_ptrs();
|
||||
int part_nr;
|
||||
int ret = 0;
|
||||
|
||||
if (elements_fit_in_base(fa))
|
||||
return ret;
|
||||
for (part_nr = 0; part_nr < max_part; part_nr++) {
|
||||
for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) {
|
||||
part = fa->parts[part_nr];
|
||||
if (!part)
|
||||
continue;
|
||||
|
|
Loading…
Reference in a new issue