linux-kernel - Re: [PATCH 9/9] clk: Overwrite clk_hw::init with NULL during clk

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Date:   Thu, 8 Aug 2019 18:14:34 +0200
From:   Sylwester Nawrocki <s.nawrocki@...sung.com>
To:     Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>
Cc:     linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Doug Anderson <dianders@...omium.org>
Subject: Re: [PATCH 9/9] clk: Overwrite clk_hw::init with NULL during
 clk_register()

On 7/31/19 21:35, Stephen Boyd wrote:
> We don't want clk provider drivers to use the init structure after clk
> registration time, but we leave a dangling reference to it by means of
> clk_hw::init. Let's overwrite the member with NULL during clk_register()
> so that this can't be used anymore after registration time.
> 
> Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
> Cc: Doug Anderson <dianders@...omium.org>
> Signed-off-by: Stephen Boyd <sboyd@...nel.org>

Reviewed-by: Sylwester Nawrocki <s.nawrocki@...sung.com>

>  drivers/clk/clk.c            | 24 ++++++++++++++++--------
>  include/linux/clk-provider.h |  3 ++-
>  2 files changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index c0990703ce54..efac620264a2 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -3484,9 +3484,9 @@ static int clk_cpy_name(const char **dst_p, const char *src, bool must_exist)
>  	return 0;
>  }
>  
> -static int clk_core_populate_parent_map(struct clk_core *core)
> +static int clk_core_populate_parent_map(struct clk_core *core,
> +					const struct clk_init_data *init)
>  {
> -	const struct clk_init_data *init = core->hw->init;
>  	u8 num_parents = init->num_parents;
>  	const char * const *parent_names = init->parent_names;
>  	const struct clk_hw **parent_hws = init->parent_hws;
> @@ -3566,6 +3566,14 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
>  {
>  	int ret;
>  	struct clk_core *core;
> +	const struct clk_init_data *init = hw->init;
> +
> +	/*
> +	 * The init data is not supposed to be used outside of registration path.
> +	 * Set it to NULL so that provider drivers can't use it either and so that
> +	 * we catch use of hw->init early on in the core.
> +	 */

nit: This comment could be re-edited to not exceed 80 columns limit.

> +	hw->init = NULL;