Re: [PATCH] clk: sunxi: Remove use of VLAIS

From: Chen-Yu Tsai
Date: Thu Mar 03 2016 - 13:07:37 EST


On Tue, Mar 1, 2016 at 4:20 PM, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote:
> Using an array allocated on the stack may lead to stack overflows
> and other problems. Furthermore, VLAIS doesn't work well with
> LLVM compilers, so move the allocation to the heap and avoid the
> use of VLAIS here.
>
> Cc: Chen-Yu Tsai <wens@xxxxxxxx>
> Cc: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
> ---
> drivers/clk/sunxi/clk-sun8i-mbus.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/sunxi/clk-sun8i-mbus.c b/drivers/clk/sunxi/clk-sun8i-mbus.c
> index 3aaa9cbef791..8e7128e69823 100644
> --- a/drivers/clk/sunxi/clk-sun8i-mbus.c
> +++ b/drivers/clk/sunxi/clk-sun8i-mbus.c
> @@ -33,7 +33,7 @@ static DEFINE_SPINLOCK(sun8i_a23_mbus_lock);
> static void __init sun8i_a23_mbus_setup(struct device_node *node)
> {
> int num_parents = of_clk_get_parent_count(node);
> - const char *parents[num_parents];
> + const char **parents;
> const char *clk_name = node->name;
> struct resource res;
> struct clk_divider *div;
> @@ -43,10 +43,14 @@ static void __init sun8i_a23_mbus_setup(struct device_node *node)
> void __iomem *reg;
> int err;
>
> + parents = kcalloc(num_parents, sizeof(*parents), GFP_KERNEL);
> + if (!parents)
> + return;
> +
> reg = of_io_request_and_map(node, 0, of_node_full_name(node));
> if (!reg) {
> pr_err("Could not get registers for sun8i-mbus-clk\n");
> - return;
> + goto err_free_parents;
> }
>
> div = kzalloc(sizeof(*div), GFP_KERNEL);
> @@ -107,6 +111,8 @@ err_free_div:
> kfree(div);
> err_unmap:
> iounmap(reg);
> +err_free_parents:
> + kfree(parents);

AFAIK the CCF makes a deep copy of parents, so you should
always free it? I specifically checked it before using
VLAIS here.

ChenYu

> of_address_to_resource(node, 0, &res);
> release_mem_region(res.start, resource_size(&res));
> }
> --
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