Re: [PATCH] mfd: arizona: fix undefined behavior

From: Charles Keepax
Date: Fri Mar 22 2019 - 13:03:50 EST

On Fri, Mar 22, 2019 at 03:33:37PM +0100, Arnd Bergmann wrote:
> When the driver is used with a subdevice that is disabled in the
> kernel configuration, clang gets a little confused about the
> control flow and fails to notice that n_subdevs is only
> uninitialized when subdevs is NULL, and we check for that,
> leading to a false-positive warning:
> drivers/mfd/arizona-core.c:1423:19: error: variable 'n_subdevs' is uninitialized when used here
> [-Werror,-Wuninitialized]
> subdevs, n_subdevs, NULL, 0, NULL);
> ^~~~~~~~~
> drivers/mfd/arizona-core.c:999:15: note: initialize the variable 'n_subdevs' to silence this warning
> int n_subdevs, ret, i;
> ^
> = 0
> Ideally, we would rearrange the code to avoid all those early
> initializations and have an explicit exit in each disabled case,
> but it's much easier to chicken out and add one more initialization
> here to shut up the warning.
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---

Acked-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx>