diff options
author | David Rientjes <rientjes@google.com> | 2009-09-21 17:04:33 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 07:17:47 -0700 |
commit | 45b588d6e5cc172704bac0c998ce54873b149b22 (patch) | |
tree | 57a9d3478af60fcf6932c1f61b083b9203ef1ee8 /include | |
parent | 4af5a2f770cc8575840ccb1514ec76ecb592985c (diff) |
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such that the array parameters are no longer valid.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 'include')
-rw-r--r-- | include/linux/flex_array.h | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h index f12401e485f..1d747f72298 100644 --- a/include/linux/flex_array.h +++ b/include/linux/flex_array.h @@ -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); |