linux-kernel - Re: [PATCH v2 3/4] platform/x86: hp-bioscfg: move mutex_lock down in hp_add_other

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Message-ID: <8ebcdb8-e1a-11ce-c42b-e73bdf55a58@linux.intel.com>
Date:   Fri, 10 Nov 2023 16:35:07 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
cc:     Jorge Lopez <jorge.lopez2@...com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <markgross@...nel.org>,
        Thomas Weißschuh <linux@...ssschuh.net>,
        platform-driver-x86@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>, dan.carpenter@...aro.org,
        kernel-janitors@...r.kernel.org, error27@...il.com,
        vegard.nossum@...cle.com, darren.kenny@...cle.com
Subject: Re: [PATCH v2 3/4] platform/x86: hp-bioscfg: move mutex_lock down
 in hp_add_other_attributes()

On Fri, 10 Nov 2023, Harshit Mogalapalli wrote:

> attr_name_kobj's memory allocation is done with mutex_lock held, this

Please use () with function names.

> probably is not needed.

Just remove probably.

> Move the mutex_lock downward so we need not unlock when allocation
> fails.

Move allocation outside of mutex_lock() so unlock is not needed when
allocation fails.

The code change looks fine.

-- 
 i.

> Suggested-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
> ---
>  drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> index 3b735b071a01..351d782f3e96 100644
> --- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> @@ -575,77 +575,75 @@ static void release_attributes_data(void)
>  /**
>   * hp_add_other_attributes() - Initialize HP custom attributes not
>   * reported by BIOS and required to support Secure Platform and Sure
>   * Start.
>   *
>   * @attr_type: Custom HP attribute not reported by BIOS
>   *
>   * Initialize all 2 types of attributes: Platform and Sure Start
>   * object.  Populates each attribute types respective properties
>   * under sysfs files.
>   *
>   * Returns zero(0) if successful. Otherwise, a negative value.
>   */
>  static int hp_add_other_attributes(int attr_type)
>  {
>  	struct kobject *attr_name_kobj;
>  	int ret;
>  	char *attr_name;
>  
> -	mutex_lock(&bioscfg_drv.mutex);
> -
>  	attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
> -	if (!attr_name_kobj) {
> -		ret = -ENOMEM;
> -		goto err_other_attr_init;
> -	}
> +	if (!attr_name_kobj)
> +		return -ENOMEM;
> +
> +	mutex_lock(&bioscfg_drv.mutex);
>  
>  	/* Check if attribute type is supported */
>  	switch (attr_type) {
>  	case HPWMI_SECURE_PLATFORM_TYPE:
>  		attr_name_kobj->kset = bioscfg_drv.authentication_dir_kset;
>  		attr_name = SPM_STR;
>  		break;
>  
>  	case HPWMI_SURE_START_TYPE:
>  		attr_name_kobj->kset = bioscfg_drv.main_dir_kset;
>  		attr_name = SURE_START_STR;
>  		break;
>  
>  	default:
>  		pr_err("Error: Unknown attr_type: %d\n", attr_type);
>  		ret = -EINVAL;
>  		goto err_other_attr_init;
>  	}
>  
>  	ret = kobject_init_and_add(attr_name_kobj, &attr_name_ktype,
>  				   NULL, "%s", attr_name);
>  	if (ret) {
>  		pr_err("Error encountered [%d]\n", ret);
>  		kobject_put(attr_name_kobj);
>  		goto err_other_attr_init;
>  	}
>  
>  	/* Populate attribute data */
>  	switch (attr_type) {
>  	case HPWMI_SECURE_PLATFORM_TYPE:
>  		ret = hp_populate_secure_platform_data(attr_name_kobj);
>  		break;
>  
>  	case HPWMI_SURE_START_TYPE:
>  		ret = hp_populate_sure_start_data(attr_name_kobj);
>  		break;
>  
>  	default:
>  		ret = -EINVAL;
>  	}
>  
>  	if (ret)
>  		goto err_other_attr_init;
>  
>  	mutex_unlock(&bioscfg_drv.mutex);
>  	return 0;
>  
>  err_other_attr_init:
>  	mutex_unlock(&bioscfg_drv.mutex);
>  	return ret;
>  }
>