Re: [PATCH v2] cgroup: avoid false positive gcc-6 warning

[Tejun Heo]

On Tue, Mar 15, 2016 at 12:21:06AM +0100, Arnd Bergmann wrote:
> When all subsystems are disabled, gcc notices that cgroup_subsys_enabled_key
> is a zero-length array and that any access to it must be out of bounds:
> 
> In file included from ../include/linux/cgroup.h:19:0,
>                  from ../kernel/cgroup.c:31:
> ../kernel/cgroup.c: In function 'cgroup_add_cftypes':
> ../kernel/cgroup.c:261:53: error: array subscript is above array bounds [-Werror=array-bounds]
>   return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
>                             ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
> ../include/linux/jump_label.h:271:40: note: in definition of macro 'static_key_enabled'
>   static_key_count((struct static_key *)x) > 0;    \
>                                         ^
> 
> We should never call the function in this particular case, so this is
> not a bug. In order to silence the warning, this adds an explicit check
> for the CGROUP_SUBSYS_COUNT==0 case.
> 
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Applied to cgroup/for-4.6.

Thanks.

-- 
tejun