Hi Weiyi, On 26/05/2020 04:43, Weiyi Lu wrote: > On Mon, 2020-05-25 at 11:08 +0200, Matthias Brugger wrote: >> >> On 25/05/2020 08:41, Weiyi Lu wrote: >>> It'd be dangerous when struct clk_core have new memebers. >>> Add the missing initial value to clk_init_data. >>> >> >> Sorry I don't really understand this commit message, can please explain. >> In any case if this is a problem, then we probably we should fix it for all drivers. >> Apart from drivers/clk/mediatek/clk-cpumux.c >> > > Actually, we were looking into an android kernel patch "ANDROID: GKI: > clk: Add support for voltage voting" [1] > > In this patch, there adds a new member struct clk_vdd_class *vdd_class; > in struct clk_init_data and struct clk_core > > And then in clk_register(...) > core->vdd_class = hw->init->vdd_class; > > In many clock APIs, it will check the core->vdd_class to select the > correct control flow. > So, if we don't assign an initial value to clk_init_data of mtk_mux > clock type, something might go wrong. And assigning an initial value > might be the easiest and good way to avoid such problem if any new clock > support added in the future. > Thanks for your explanation. You mean that as clk_init_data is on the stack it can have random values, and would lead to the fact that vdd_class is interpreted as allocated although it should be NULL. Sounds reasonable to me. You might want to resend with a better commit message. Feel free to add my Reviewed-by: Matthias Brugger <matthias.bgg@xxxxxxxxx> Regards, Matthias > [1] https://android-review.googlesource.com/c/kernel/common/+/1278046 > >> It's a widely used pattern: >> $ git grep "struct clk_init_data init;"| wc -l >> 235 >> >> Regards, >> Matthias >> >>> Fixes: a3ae549917f1 ("clk: mediatek: Add new clkmux register API") >>> Cc: <stable@xxxxxxxxxxxxxxx> >>> Signed-off-by: Weiyi Lu <weiyi.lu@xxxxxxxxxxxx> >>> --- >>> drivers/clk/mediatek/clk-mux.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/clk/mediatek/clk-mux.c b/drivers/clk/mediatek/clk-mux.c >>> index 76f9cd0..14e127e 100644 >>> --- a/drivers/clk/mediatek/clk-mux.c >>> +++ b/drivers/clk/mediatek/clk-mux.c >>> @@ -160,7 +160,7 @@ struct clk *mtk_clk_register_mux(const struct mtk_mux *mux, >>> spinlock_t *lock) >>> { >>> struct mtk_clk_mux *clk_mux; >>> - struct clk_init_data init; >>> + struct clk_init_data init = {}; >>> struct clk *clk; >>> >>> clk_mux = kzalloc(sizeof(*clk_mux), GFP_KERNEL); >>> >
