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authorDavid Rientjes <rientjes@google.com>2009-09-21 17:04:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:17:47 -0700
commit45b588d6e5cc172704bac0c998ce54873b149b22 (patch)
tree57a9d3478af60fcf6932c1f61b083b9203ef1ee8 /lib/flex_array.c
parent4af5a2f770cc8575840ccb1514ec76ecb592985c (diff)
downloadvexpress-lsk-45b588d6e5cc172704bac0c998ce54873b149b22.tar.gz
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the kernel build will fail if either of these predefined values changes such that the array parameters are no longer valid.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>
Diffstat (limited to 'lib/flex_array.c')
-rw-r--r--lib/flex_array.c36
1 files changed, 10 insertions, 26 deletions
diff --git a/lib/flex_array.c b/lib/flex_array.c
index 1b03bb55341..b62ce6cffd0 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;
}
@@ -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;