linux-kernel - Re: [PATCH V3] clocksource/drivers/tango_xtal: Convert init function to return error

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Date:	Fri, 17 Jun 2016 14:35:19 +0200
From:	Marc Gonzalez <marc_gonzalez@...madesigns.com>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>, Mason <slash.tmp@...e.fr>,
	Sebastian Frias <sf84@...oste.net>
Subject: Re: [PATCH V3] clocksource/drivers/tango_xtal: Convert init function
 to return error

On 17/06/2016 12:26, 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
                         ^^^                    ^^
"leave the caller unaware of [...]" (?)

> 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
                                 ^^^^^^^^^^^
"just returns an error code from the init function" (?)

> function.
> 
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> ---
>  drivers/clocksource/tango_xtal.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clocksource/tango_xtal.c b/drivers/clocksource/tango_xtal.c
> index c407c47..7dc716c 100644
> --- a/drivers/clocksource/tango_xtal.c
> +++ b/drivers/clocksource/tango_xtal.c
> @@ -19,7 +19,7 @@ static u64 notrace read_sched_clock(void)
>  	return read_xtal_counter();
>  }
>  
> -static void __init tango_clocksource_init(struct device_node *np)
> +static int __init tango_clocksource_init(struct device_node *np)
>  {
>  	struct clk *clk;
>  	int xtal_freq, ret;
> @@ -27,13 +27,13 @@ static void __init tango_clocksource_init(struct device_node *np)
>  	xtal_in_cnt = of_iomap(np, 0);
>  	if (xtal_in_cnt == NULL) {
>  		pr_err("%s: invalid address\n", np->full_name);
> -		return;
> +		return -ENXIO;
>  	}
>  
>  	clk = of_clk_get(np, 0);
>  	if (IS_ERR(clk)) {
>  		pr_err("%s: invalid clock\n", np->full_name);
> -		return;
> +		return PTR_ERR(clk);
>  	}
>  
>  	xtal_freq = clk_get_rate(clk);
> @@ -44,11 +44,13 @@ static void __init tango_clocksource_init(struct device_node *np)
>  				    32, clocksource_mmio_readl_up);
>  	if (ret) {
>  		pr_err("%s: registration failed\n", np->full_name);
> -		return;
> +		return ret;
>  	}
>  
>  	sched_clock_register(read_sched_clock, 32, xtal_freq);
>  	register_current_timer_delay(&delay_timer);
> +
> +	return 0;
>  }
>  
> -CLOCKSOURCE_OF_DECLARE(tango, "sigma,tick-counter", tango_clocksource_init);
> +CLOCKSOURCE_OF_DECLARE_RET(tango, "sigma,tick-counter", tango_clocksource_init);

The code looks good to me.
Acked-by: Marc Gonzalez <marc_gonzalez@...madesigns.com>

Could you merge, on top of these, the patch we discussed a few weeks ago
for changing ret to err? (I will attach the patch to this message.)

Regards.