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author | David Rientjes <rientjes@google.com> | 2009-09-21 17:04:33 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 07:17:47 -0700 |
commit | 45b588d6e5cc172704bac0c998ce54873b149b22 (patch) | |
tree | 57a9d3478af60fcf6932c1f61b083b9203ef1ee8 /lib | |
parent | 4af5a2f770cc8575840ccb1514ec76ecb592985c (diff) | |
download | linux-stable-45b588d6e5cc172704bac0c998ce54873b149b22.tar.gz linux-stable-45b588d6e5cc172704bac0c998ce54873b149b22.tar.bz2 linux-stable-45b588d6e5cc172704bac0c998ce54873b149b22.zip |
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such that the array parameters are no longer valid.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')
-rw-r--r-- | lib/flex_array.c | 36 |
1 files changed, 10 insertions, 26 deletions
diff --git a/lib/flex_array.c b/lib/flex_array.c index 1b03bb553410..b62ce6cffd0a 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; |