The patch titled
flex_array: introduce DEFINE_FLEX_ARRAY
has been added to the -mm tree. Its filename is
flex_array-introduce-define_flex_array.patch
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------------------------------------------------------
Subject: flex_array: introduce DEFINE_FLEX_ARRAY
From: David Rientjes <rientjes@xxxxxxxxxx>
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such that the array parameters are no longer valid.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@xxxxxxxxxx>
Acked-by: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/flex_array.h | 30 +++++++++++++++++++++++++----
lib/flex_array.c | 36 +++++++++--------------------------
2 files changed, 36 insertions(+), 30 deletions(-)
diff -puN include/linux/flex_array.h~flex_array-introduce-define_flex_array include/linux/flex_array.h
--- a/include/linux/flex_array.h~flex_array-introduce-define_flex_array
+++ a/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);
diff -puN lib/flex_array.c~flex_array-introduce-define_flex_array lib/flex_array.c
--- a/lib/flex_array.c~flex_array-introduce-define_flex_array
+++ a/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
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
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
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(st
{
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_arra
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;
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
linux-next.patch
mm-remove-obsoleted-alloc_pages-cpuset-comment.patch
hugetlb-balance-freeing-of-huge-pages-across-nodes.patch
hugetlb-use-free_pool_huge_page-to-return-unused-surplus-pages.patch
hugetlb-use-free_pool_huge_page-to-return-unused-surplus-pages-fix.patch
hugetlb-clean-up-and-update-huge-pages-documentation.patch
mm-oom-analysis-add-per-zone-statistics-to-show_free_areas.patch
mm-oom-analysis-add-buffer-cache-information-to-show_free_areas.patch
mm-oom-analysis-show-kernel-stack-usage-in-proc-meminfo-and-oom-log-output.patch
mm-oom-analysis-add-shmem-vmstat.patch
mm-update-alloc_flags-after-oom-killer-has-been-called.patch
pagemap-clear_refs-modify-to-specify-anon-or-mapped-vma-clearing.patch
oom-move-oom_killer_enable-oom_killer_disable-to-where-they-belong.patch
hugetlbfs-allow-the-creation-of-files-suitable-for-map_private-on-the-vfs-internal-mount.patch
hugetlb-add-map_hugetlb-for-mmaping-pseudo-anonymous-huge-page-regions.patch
hugetlb-add-map_hugetlb-example.patch
oom-move-oom_adj-value-from-task_struct-to-signal_struct.patch
oom-make-oom_score-to-per-process-value.patch
oom-oom_kill-doesnt-kill-vfork-parentor-child.patch
oom-fix-oom_adjust_write-input-sanity-check.patch
flex_array-add-flex_array_clear-function.patch
flex_array-poison-free-elements.patch
flex_array-add-flex_array_shrink-function.patch
flex_array-introduce-define_flex_array.patch
flex_array-add-missing-kerneldoc-annotations.patch
fs-proc-task_mmuc-v1-fix-clear_refs_write-input-sanity-check.patch
do_wait-optimization-do-not-place-sub-threads-on-task_struct-children-list.patch
--
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