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authorEric Paris <eparis@redhat.com>2011-04-28 21:55:52 +0200
committerEric Paris <eparis@redhat.com>2011-04-28 21:56:07 +0200
commita8d05c81fb238bbb18878ccfae7599ca79448dd3 (patch)
treeb66baaf076be8f830cc07fb02ad22e2b3a9dd3e2 /lib/flex_array.c
parentflex_arrays: allow zero length flex arrays (diff)
downloadlinux-a8d05c81fb238bbb18878ccfae7599ca79448dd3.tar.xz
linux-a8d05c81fb238bbb18878ccfae7599ca79448dd3.zip
flex_array: allow 0 length elements
flex_arrays are supposed to be a replacement for: kmalloc(num_elements * sizeof(element)) If kmalloc is given 0 num_elements or a 0 size element it will happily return ZERO_SIZE_PTR. Which looks like a valid allocation, but which will explode if something actually try to use it. The current flex_array code will return an equivalent result if num_elements is 0, but will fail to work if sizeof(element) is 0. This patch allows allocation to work even for 0 size elements. It will cause flex_arrays to explode though if they are used. Imitating the kmalloc behavior. Based-on-patch-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>
Diffstat (limited to 'lib/flex_array.c')
-rw-r--r--lib/flex_array.c26
1 files changed, 20 insertions, 6 deletions
diff --git a/lib/flex_array.c b/lib/flex_array.c
index 854b57bd7d9d..cab7621f98aa 100644
--- a/lib/flex_array.c
+++ b/lib/flex_array.c
@@ -88,8 +88,11 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total,
gfp_t flags)
{
struct flex_array *ret;
- int max_size = FLEX_ARRAY_NR_BASE_PTRS *
- FLEX_ARRAY_ELEMENTS_PER_PART(element_size);
+ int max_size = 0;
+
+ if (element_size)
+ 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)
@@ -183,15 +186,18 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags)
int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
gfp_t flags)
{
- int part_nr = fa_element_to_part_nr(fa, element_nr);
+ int part_nr;
struct flex_array_part *part;
void *dst;
if (element_nr >= fa->total_nr_elements)
return -ENOSPC;
+ if (!fa->element_size)
+ return 0;
if (elements_fit_in_base(fa))
part = (struct flex_array_part *)&fa->parts[0];
else {
+ part_nr = fa_element_to_part_nr(fa, element_nr);
part = __fa_get_part(fa, part_nr, flags);
if (!part)
return -ENOMEM;
@@ -211,15 +217,18 @@ EXPORT_SYMBOL(flex_array_put);
*/
int flex_array_clear(struct flex_array *fa, unsigned int element_nr)
{
- int part_nr = fa_element_to_part_nr(fa, element_nr);
+ int part_nr;
struct flex_array_part *part;
void *dst;
if (element_nr >= fa->total_nr_elements)
return -ENOSPC;
+ if (!fa->element_size)
+ return 0;
if (elements_fit_in_base(fa))
part = (struct flex_array_part *)&fa->parts[0];
else {
+ part_nr = fa_element_to_part_nr(fa, element_nr);
part = fa->parts[part_nr];
if (!part)
return -EINVAL;
@@ -264,6 +273,8 @@ int flex_array_prealloc(struct flex_array *fa, unsigned int start,
if (end >= fa->total_nr_elements)
return -ENOSPC;
+ if (!fa->element_size)
+ return 0;
if (elements_fit_in_base(fa))
return 0;
start_part = fa_element_to_part_nr(fa, start);
@@ -291,14 +302,17 @@ EXPORT_SYMBOL(flex_array_prealloc);
*/
void *flex_array_get(struct flex_array *fa, unsigned int element_nr)
{
- int part_nr = fa_element_to_part_nr(fa, element_nr);
+ int part_nr;
struct flex_array_part *part;
+ if (!fa->element_size)
+ return NULL;
if (element_nr >= fa->total_nr_elements)
return NULL;
if (elements_fit_in_base(fa))
part = (struct flex_array_part *)&fa->parts[0];
else {
+ part_nr = fa_element_to_part_nr(fa, element_nr);
part = fa->parts[part_nr];
if (!part)
return NULL;
@@ -353,7 +367,7 @@ int flex_array_shrink(struct flex_array *fa)
int part_nr;
int ret = 0;
- if (!fa->total_nr_elements)
+ if (!fa->total_nr_elements || !fa->element_size)
return 0;
if (elements_fit_in_base(fa))
return ret;