Subject: Re: [PATCH] clk: kirkwood: use kzalloc_flex

From: Brian Masney <[email-masked]>
Date: Mon, 30 Mar 2026 09:13:04 -0400

On Wed, Mar 25, 2026 at 09:55:55PM -0700, Rosen Penev wrote:
> Simplify allocation by using a flexible array member and kzalloc_flex to
> combine allocations.
> 
> Add __counted_by for extra runtime analysis. Move counting variable
> assignment to right after allocation as required by __counted_by.
> 
> Signed-off-by: Rosen Penev <[email-masked]>
> ---
>  drivers/clk/mvebu/kirkwood.c | 19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/clk/mvebu/kirkwood.c b/drivers/clk/mvebu/kirkwood.c
> index ed061d82fb65..fc2972538008 100644
> --- a/drivers/clk/mvebu/kirkwood.c
> +++ b/drivers/clk/mvebu/kirkwood.c
> @@ -253,8 +253,8 @@ struct clk_muxing_soc_desc {
>  
>  struct clk_muxing_ctrl {
>  	spinlock_t *lock;
> -	struct clk **muxes;
>  	int num_muxes;
> +	struct clk *muxes[] __counted_by(num_muxes);
>  };
>  
>  static const char *powersave_parents[] = {
> @@ -297,21 +297,18 @@ static void __init kirkwood_clk_muxing_setup(struct device_node *np,
>  	if (WARN_ON(!base))
>  		return;
>  
> -	ctrl = kzalloc_obj(*ctrl);
> -	if (WARN_ON(!ctrl))
> -		goto ctrl_out;
> -
> -	/* lock must already be initialized */
> -	ctrl->lock = &ctrl_gating_lock;
> -
>  	/* Count, allocate, and register clock muxes */
>  	for (n = 0; desc[n].name;)
>  		n++;
>  
> +	ctrl = kzalloc_flex(*ctrl, muxes, n);
> +	if (WARN_ON(!ctrl))
> +		goto ctrl_out;
> +
>  	ctrl->num_muxes = n;
> -	ctrl->muxes = kzalloc_objs(struct clk *, ctrl->num_muxes);
> -	if (WARN_ON(!ctrl->muxes))
> -		goto muxes_out;

Question from Sashiko:

https://sashiko.dev/#/patchset/20260326045555.240730-1-rosenp%40gmail.com

    This isn't a bug, but since the goto muxes_out error path was removed here,
    should the muxes_out label and its kfree(ctrl) be removed at the end of the
    function?
    They appear to be dead code now and might cause an unused label warning:
    	return;
    muxes_out:
    	kfree(ctrl);
    ctrl_out:
    	iounmap(base);
    }

Brian

> +
> +	/* lock must already be initialized */
> +	ctrl->lock = &ctrl_gating_lock;
>  
>  	for (n = 0; n < ctrl->num_muxes; n++) {
>  		ctrl->muxes[n] = clk_register_mux(NULL, desc[n].name,
> -- 
> 2.53.0
>