[PATCH] docs: deprecated.rst: Update zero-length/one-element arrays section

[PATCH] docs: deprecated.rst: Update zero-length/one-element arrays section

[Gustavo A. R. Silva]

Update information in the zero-length and one-element arrays section
and illustrate how to make use of the new flex_array_size() helper,
together with struct_size() and a flexible-array member.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 Documentation/process/deprecated.rst | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index 918e32d76fc4..9731704b3f3d 100644
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -322,7 +322,8 @@ to allocate for a structure containing an array of this kind as a member::
 In the example above, we had to remember to calculate ``count - 1`` when using
 the struct_size() helper, otherwise we would have --unintentionally-- allocated
 memory for one too many ``items`` objects. The cleanest and least error-prone way
-to implement this is through the use of a `flexible array member`::
+to implement this is through the use of a `flexible array member`, together with
+struct_size() and flex_array_size() helpers::
 
         struct something {
                 size_t count;
@@ -334,5 +335,4 @@ to implement this is through the use of a `flexible array member`::
         instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL);
         instance->count = count;
 
-        size = sizeof(instance->items[0]) * instance->count;
-        memcpy(instance->items, source, size);
+        memcpy(instance->items, source, flex_array_size(instance, items, instance->count));
-- 
2.27.0

Re: [PATCH] docs: deprecated.rst: Update zero-length/one-element arrays section

[Kees Cook]

On Mon, Aug 31, 2020 at 08:09:49PM -0500, Gustavo A. R. Silva wrote:
> Update information in the zero-length and one-element arrays section
> and illustrate how to make use of the new flex_array_size() helper,
> together with struct_size() and a flexible-array member.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Looks great!

Acked-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH] docs: deprecated.rst: Update zero-length/one-element arrays section

[Jonathan Corbet]

On Mon, 31 Aug 2020 20:09:49 -0500
"Gustavo A. R. Silva" <gustavoars@kernel.org> wrote:

> Update information in the zero-length and one-element arrays section
> and illustrate how to make use of the new flex_array_size() helper,
> together with struct_size() and a flexible-array member.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> ---
>  Documentation/process/deprecated.rst | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Applied, thanks.

jon

Re: [PATCH] docs: deprecated.rst: Update zero-length/one-element arrays section

[Gustavo A. R. Silva]

On Wed, Sep 09, 2020 at 11:38:23AM -0600, Jonathan Corbet wrote:
> On Mon, 31 Aug 2020 20:09:49 -0500
> "Gustavo A. R. Silva" <gustavoars@kernel.org> wrote:
> 
> > Update information in the zero-length and one-element arrays section
> > and illustrate how to make use of the new flex_array_size() helper,
> > together with struct_size() and a flexible-array member.
> > 
> > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> > ---
> >  Documentation/process/deprecated.rst | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> Applied, thanks.

Thank you, both. :)

--
Gustavo