Re: [PATCH] clk: microchip: mpfs-ccc: Use devm_kasprintf() for allocating formatted strings

[Conor Dooley <conor@kernel.org>]

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On Tue, Jan 03, 2023 at 05:45:30PM +0100, Geert Uytterhoeven wrote:
> In various places, string buffers of a fixed size are allocated, and
> filled using snprintf() with the same fixed size, which is error-prone.
> 
> Replace this by calling devm_kasprintf() instead, which always uses the
> appropriate size.
> 
> While at it, remove an unneeded intermediate variable, which allows us
> to drop a cast as a bonus.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>

I half wonder if this should actually have a fixes tag too. Since it
used what came after the @ in $full_name, it'd be possible to create
(an incorrect) DTS that would lead to a clash between pll names &
therefore probe would fail.
The tag would be:
Fixes: d39fb172760e ("clk: microchip: add PolarFire SoC fabric clock support")

Either way, thanks for pointing out a function that does exactly what I
initially wanted to do but could not find! Glad to be rid of those
"oddly specific" allocations.

Thanks,
Conor.
> ---
>  drivers/clk/microchip/clk-mpfs-ccc.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/clk/microchip/clk-mpfs-ccc.c b/drivers/clk/microchip/clk-mpfs-ccc.c
> index 32aae880a14f3b1c..0ddc73e07be42973 100644
> --- a/drivers/clk/microchip/clk-mpfs-ccc.c
> +++ b/drivers/clk/microchip/clk-mpfs-ccc.c
> @@ -164,12 +164,11 @@ static int mpfs_ccc_register_outputs(struct device *dev, struct mpfs_ccc_out_hw_
>  
>  	for (unsigned int i = 0; i < num_clks; i++) {
>  		struct mpfs_ccc_out_hw_clock *out_hw = &out_hws[i];
> -		char *name = devm_kzalloc(dev, 23, GFP_KERNEL);
> +		char *name = devm_kasprintf(dev, GFP_KERNEL, "%s_out%u", parent->name, i);
>  
>  		if (!name)
>  			return -ENOMEM;
>  
> -		snprintf(name, 23, "%s_out%u", parent->name, i);
>  		out_hw->divider.hw.init = CLK_HW_INIT_HW(name, &parent->hw, &clk_divider_ops, 0);
>  		out_hw->divider.reg = data->pll_base[i / MPFS_CCC_OUTPUTS_PER_PLL] +
>  			out_hw->reg_offset;
> @@ -201,14 +200,13 @@ static int mpfs_ccc_register_plls(struct device *dev, struct mpfs_ccc_pll_hw_clo
>  
>  	for (unsigned int i = 0; i < num_clks; i++) {
>  		struct mpfs_ccc_pll_hw_clock *pll_hw = &pll_hws[i];
> -		char *name = devm_kzalloc(dev, 18, GFP_KERNEL);
>  
> -		if (!name)
> +		pll_hw->name = devm_kasprintf(dev, GFP_KERNEL, "ccc%s_pll%u",
> +					      strchrnul(dev->of_node->full_name, '@'), i);
> +		if (!pll_hw->name)
>  			return -ENOMEM;
>  
>  		pll_hw->base = data->pll_base[i];
> -		snprintf(name, 18, "ccc%s_pll%u", strchrnul(dev->of_node->full_name, '@'), i);
> -		pll_hw->name = (const char *)name;
>  		pll_hw->hw.init = CLK_HW_INIT_PARENTS_DATA_FIXED_SIZE(pll_hw->name,
>  								      pll_hw->parents,
>  								      &mpfs_ccc_pll_ops, 0);
> -- 
> 2.25.1
> 
> 

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