linux-kernel - Re: [PATCH] clk: mvebu/clk-cpu.c: fix memory leakage

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Message-ID: <50F563EC.3030804@free-electrons.com>
Date:	Tue, 15 Jan 2013 15:13:00 +0100
From:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
To:	Cong Ding <dinggnu@...il.com>
CC:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	linux-kernel@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] clk: mvebu/clk-cpu.c: fix memory leakage

Dear Cong Ding,

On 01/14/2013 06:18 PM, Cong Ding wrote:
> the variable cpuclk and clk_name should be properly freed.
> 

Thanks for reporting this memory leak and for your patch but I think
we could do even better, see below:

> Signed-off-by: Cong Ding <dinggnu@...il.com>
> ---
>  drivers/clk/mvebu/clk-cpu.c |    9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/mvebu/clk-cpu.c b/drivers/clk/mvebu/clk-cpu.c
> index ff004578..1a0d84f 100644
> --- a/drivers/clk/mvebu/clk-cpu.c
> +++ b/drivers/clk/mvebu/clk-cpu.c
> @@ -124,7 +124,7 @@ void __init of_cpu_clk_setup(struct device_node *node)
>  
>  	clks = kzalloc(ncpus * sizeof(*clks), GFP_KERNEL);
>  	if (WARN_ON(!clks))
> -		return;
> +		goto clks_out;
>  
>  	for_each_node_by_type(dn, "cpu") {
>  		struct clk_init_data init;
> @@ -134,11 +134,11 @@ void __init of_cpu_clk_setup(struct device_node *node)
>  		int cpu, err;
>  
>  		if (WARN_ON(!clk_name))
> -			return;
> +			goto clk_name_out;

I agree

>  
>  		err = of_property_read_u32(dn, "reg", &cpu);
>  		if (WARN_ON(err))
> -			return;
> +			goto bail_out;

I agree

>  
>  		sprintf(clk_name, "cpu%d", cpu);
>  		parent_clk = of_clk_get(node, 0);
> @@ -166,7 +166,10 @@ void __init of_cpu_clk_setup(struct device_node *node)
>  
>  	return;
>  bail_out:
> +	kfree(clk_name);

Here you free only one clk_name whereas we could have previous clk_name which have
been already allocated during the for_each_node_by_type loop.

A more annoying thing is that you use clk_name whereas it is only valid in the
for_each_node_by_type statement and then this patch breaks the compilation:

drivers/clk/mvebu/clk-cpu.c: In function ‘of_cpu_clk_setup’:
drivers/clk/mvebu/clk-cpu.c:169:8: error: ‘clk_name’ undeclared (first use in this function)
drivers/clk/mvebu/clk-cpu.c:169:8: note: each undeclared identifier is reported only once for each function it appears in

Thanks,

Gregory
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