Re: [PATCH 5/9] clocksource/drivers/exynos_mct: Convert init function to return error

[Krzysztof Kozlowski <k.kozlowski@samsung.com>]

On 06/01/2016 10:34 AM, Daniel Lezcano wrote:
> The init functions do not return any error. They behave as the following:
> 
>  - panic, thus leading to a kernel crash while another timer may work and
>    make the system boot up correctly
> 
>  or
> 
>  - print an error and let the caller unaware if the state of the system
> 
> Change that by converting the init functions to return an error conforming
> to the CLOCKSOURCE_OF_RET prototype.
> 
> Proper error handling (rollback, errno value) will be changed later case
> by case, thus this change just return back an error or success in the init
> function.

I don't see the benefits of this change alone. You are replacing one
non-return code to another always-return-success code. The effect is
exactly the same. It would make sense to change it to CLOCKSOURCE_OF_RET
along with proper error handling.

Best regards,
Krzysztof

> 
> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> ---
>  drivers/clocksource/exynos_mct.c | 36 ++++++++++++++++++++++++------------
>  1 file changed, 24 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
> index be09bc0..f6caed0 100644
> --- a/drivers/clocksource/exynos_mct.c
> +++ b/drivers/clocksource/exynos_mct.c
> @@ -232,7 +232,7 @@ static cycles_t exynos4_read_current_timer(void)
>  	return exynos4_read_count_32();
>  }
>  
> -static void __init exynos4_clocksource_init(void)
> +static int __init exynos4_clocksource_init(void)
>  {
>  	exynos4_mct_frc_start();
>  
> @@ -244,6 +244,8 @@ static void __init exynos4_clocksource_init(void)
>  		panic("%s: can't register clocksource\n", mct_frc.name);
>  
>  	sched_clock_register(exynos4_read_sched_clock, 32, clk_rate);
> +
> +	return 0;
>  }
>  
>  static void exynos4_mct_comp0_stop(void)
> @@ -335,12 +337,14 @@ static struct irqaction mct_comp_event_irq = {
>  	.dev_id		= &mct_comp_device,
>  };
>  
> -static void exynos4_clockevent_init(void)
> +static int exynos4_clockevent_init(void)
>  {
>  	mct_comp_device.cpumask = cpumask_of(0);
>  	clockevents_config_and_register(&mct_comp_device, clk_rate,
>  					0xf, 0xffffffff);
>  	setup_irq(mct_irqs[MCT_G0_IRQ], &mct_comp_event_irq);
> +
> +	return 0;
>  }
>  
>  static DEFINE_PER_CPU(struct mct_clock_event_device, percpu_mct_tick);
> @@ -516,7 +520,7 @@ static struct notifier_block exynos4_mct_cpu_nb = {
>  	.notifier_call = exynos4_mct_cpu_notify,
>  };
>  
> -static void __init exynos4_timer_resources(struct device_node *np, void __iomem *base)
> +static int __init exynos4_timer_resources(struct device_node *np, void __iomem *base)
>  {
>  	int err, cpu;
>  	struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick);
> @@ -572,15 +576,17 @@ static void __init exynos4_timer_resources(struct device_node *np, void __iomem
>  
>  	/* Immediately configure the timer on the boot CPU */
>  	exynos4_local_timer_setup(mevt);
> -	return;
> +	return 0;
>  
>  out_irq:
>  	free_percpu_irq(mct_irqs[MCT_L0_IRQ], &percpu_mct_tick);
> +	return err;
>  }
>  
> -static void __init mct_init_dt(struct device_node *np, unsigned int int_type)
> +static int __init mct_init_dt(struct device_node *np, unsigned int int_type)
>  {
>  	u32 nr_irqs, i;
> +	int ret;
>  
>  	mct_int_type = int_type;
>  
> @@ -600,20 +606,26 @@ static void __init mct_init_dt(struct device_node *np, unsigned int int_type)
>  	for (i = MCT_L0_IRQ; i < nr_irqs; i++)
>  		mct_irqs[i] = irq_of_parse_and_map(np, i);
>  
> -	exynos4_timer_resources(np, of_iomap(np, 0));
> -	exynos4_clocksource_init();
> -	exynos4_clockevent_init();
> +	ret = exynos4_timer_resources(np, of_iomap(np, 0));
> +	if (ret)
> +		return ret;
> +
> +	ret = exynos4_clocksource_init();
> +	if (ret)
> +		return ret;
> +
> +	return exynos4_clockevent_init();
>  }
>  
>  
> -static void __init mct_init_spi(struct device_node *np)
> +static int __init mct_init_spi(struct device_node *np)
>  {
>  	return mct_init_dt(np, MCT_INT_SPI);
>  }
>  
> -static void __init mct_init_ppi(struct device_node *np)
> +static int __init mct_init_ppi(struct device_node *np)
>  {
>  	return mct_init_dt(np, MCT_INT_PPI);
>  }
> -CLOCKSOURCE_OF_DECLARE(exynos4210, "samsung,exynos4210-mct", mct_init_spi);
> -CLOCKSOURCE_OF_DECLARE(exynos4412, "samsung,exynos4412-mct", mct_init_ppi);
> +CLOCKSOURCE_OF_DECLARE_RET(exynos4210, "samsung,exynos4210-mct", mct_init_spi);
> +CLOCKSOURCE_OF_DECLARE_RET(exynos4412, "samsung,exynos4412-mct", mct_init_ppi);
>