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| author | Eric Paris <eparis@redhat.com> | 2011-04-28 15:55:52 -0400 |
|---|---|---|
| committer | Eric Paris <eparis@redhat.com> | 2011-04-28 15:56:07 -0400 |
| commit | a8d05c81fb238bbb18878ccfae7599ca79448dd3 (patch) | |
| tree | b66baaf076be8f830cc07fb02ad22e2b3a9dd3e2 /lib/flex_array.c | |
| parent | 150cdf6ec0ede8d9f102f1817212447727dcf08c (diff) | |
| download | lwn-a8d05c81fb238bbb18878ccfae7599ca79448dd3.tar.gz lwn-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.c | 26 |
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; |