From 17dca0502314fa4855fae269dc86a1ce840a4d1a Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 31 Aug 2020 20:09:49 -0500 Subject: [PATCH] docs: deprecated.rst: Update zero-length/one-element arrays section 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 Acked-by: Kees Cook Link: https://lore.kernel.org/r/20200901010949.GA21398@embeddedor Signed-off-by: Jonathan Corbet --- 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 70720f00b9aa..ff71d802b53d 100644 --- a/Documentation/process/deprecated.rst +++ b/Documentation/process/deprecated.rst @@ -304,7 +304,8 @@ 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; @@ -316,5 +317,4 @@ 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));