Re: [PATCH] container_of.h: make container_of const-aware

[Andrew Morton]

On Thu, 10 Feb 2022 20:04:34 +0300 Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> wrote:

> container_of() macro has one major drawback. It does not check whether
> the passed ptr has a const pointer, the result will always be a
> non-const pointer. Use a _Generic() construct (supported since gcc 4.9
> and Clang 3.0) to teach container_of that if converting a const pointer,
> the returned pointer should also have the const modifier.
> 

Nice idea, but my x86_64 allnoconfig build explodes with zillions of
warnings.

In file included from ./include/linux/list.h:5,
                 from ./include/linux/module.h:12,
                 from init/do_mounts.c:2:
./include/net/sock.h: In function 'sk_entry':
./include/linux/container_of.h:17:42: warning: return discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]