linux-kernel - Re: [PATCH v2 1/3] ARM: imx: Add common imx cpuidle init functionality.

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Message-ID: <20120502072701.GR4141@pengutronix.de>
Date:	Wed, 2 May 2012 09:27:01 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Robert Lee <rob.lee@...aro.org>
Cc:	kernel@...gutronix.de, shawn.guo@...aro.org,
	amit.kucheria@...aro.org, daniel.lezcano@...aro.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linaro-dev@...ts.linaro.org, patches@...aro.org, jj@...osbits.net
Subject: Re: [PATCH v2 1/3] ARM: imx: Add common imx cpuidle init
 functionality.

On Tue, May 01, 2012 at 09:12:38PM -0500, Robert Lee wrote:
> Add common cpuidle init functionality that can be used by various
> imx platforms.
> 
> Signed-off-by: Robert Lee <rob.lee@...aro.org>
> ---
> +
> +int __init imx_cpuidle_init(struct cpuidle_driver *drv)
> +{
> +	struct cpuidle_device *dev;
> +	int cpu_id, ret;
> +
> +	if (!drv || drv->state_count > CPUIDLE_STATE_MAX) {

Please don't check for !drv here. When someone calls this function with
a NULL pointer he should get a nive stack trace allowing him to figure
out what went wrong.

> +		pr_err("%s: Invalid Input\n", __func__);
> +		return -EINVAL;
> +	}
> +
> +	ret = cpuidle_register_driver(drv);
> +	if (ret) {
> +		pr_err("%s: Failed to register cpuidle driver with error: %d\n",
> +			 __func__, ret);
> +		return ret;
> +	}
> +
> +	imx_cpuidle_devices = alloc_percpu(struct cpuidle_device);
> +	if (imx_cpuidle_devices == NULL) {
> +		ret = -ENOMEM;
> +		goto unregister_drv;
> +	}
> +
> +	/* initialize state data for each cpuidle_device */
> +	for_each_possible_cpu(cpu_id) {
> +		dev = per_cpu_ptr(imx_cpuidle_devices, cpu_id);
> +		dev->cpu = cpu_id;
> +		dev->state_count = drv->state_count;
> +
> +		ret = cpuidle_register_device(dev);
> +		if (ret) {
> +			pr_err("%s: Failed to register cpu %u\n",
> +				__func__, cpu_id);
> +			goto uninit;

You should only unregister the cpuidle devices you successfully
registered. Unregistering not yet registered cpuidle devices probably
has unwanted side effects.

Sascha

> +		}
> +	}
> +
> +	return 0;
> +
> +uninit:
> +	imx_cpuidle_devices_uninit();
> +
> +unregister_drv:
> +	cpuidle_unregister_driver(drv);
> +	return ret;
> +}
> diff --git a/arch/arm/plat-mxc/include/mach/cpuidle.h b/arch/arm/plat-mxc/include/mach/cpuidle.h
> new file mode 100644
> index 0000000..8612510
> --- /dev/null
> +++ b/arch/arm/plat-mxc/include/mach/cpuidle.h
> @@ -0,0 +1,22 @@
> +/*
> + * Copyright 2012 Freescale Semiconductor, Inc.
> + * Copyright 2012 Linaro Ltd.
> + *
> + * The code contained herein is licensed under the GNU General Public
> + * License. You may obtain a copy of the GNU General Public License
> + * Version 2 or later at the following locations:
> + *
> + * http://www.opensource.org/licenses/gpl-license.html
> + * http://www.gnu.org/copyleft/gpl.html
> + */
> +
> +#include <linux/cpuidle.h>
> +
> +#ifdef CONFIG_CPU_IDLE
> +extern void imx_cpuidle_devices_uninit(void);
> +extern int imx_cpuidle_init(struct cpuidle_driver *drv);
> +#else
> +static inline void imx_cpuidle_devices_uninit(void) {}
> +static inline int imx_cpuidle_init(struct cpuidle_driver *drv)
> +{ return -ENODEV; }
> +#endif
> -- 
> 1.7.10
> 
> 

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