linux-kernel - Re: [PATCH v3 2/4] of: overlay: global sysfs enable attribute

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Date:	Mon, 27 Apr 2015 21:25:03 +0300
From:	Pantelis Antoniou <pantelis.antoniou@...sulko.com>
To:	Greg KH <greg@...ah.com>
Cc:	Rob Herring <robherring2@...il.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Matt Porter <mporter@...sulko.com>,
	Koen Kooi <koen@...inion.thruhere.net>,
	Guenter Roeck <linux@...ck-us.net>, devicetree@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-api@...r.kernel.org
Subject: Re: [PATCH v3 2/4] of: overlay: global sysfs enable attribute

Hi Greg,

> On Apr 24, 2015, at 23:36 , Greg KH <greg@...ah.com> wrote:
> 
> On Fri, Apr 24, 2015 at 12:45:42PM +0300, Pantelis Antoniou wrote:
>> A throw once master enable switch to protect against any
>> further overlay applications if the administrator desires so.
>> 
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@...sulko.com>
>> ---
>> drivers/of/overlay.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 44 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>> index f17f5ef..c335809 100644
>> --- a/drivers/of/overlay.c
>> +++ b/drivers/of/overlay.c
>> @@ -21,6 +21,7 @@
>> #include <linux/err.h>
>> #include <linux/idr.h>
>> #include <linux/sysfs.h>
>> +#include <linux/atomic.h>
>> 
>> #include "of_private.h"
>> 
>> @@ -55,8 +56,12 @@ struct of_overlay {
>> 	struct kobject kobj;
>> };
>> 
>> +/* master enable switch; once set to 0 can't be re-enabled */
>> +static atomic_t ov_enable = ATOMIC_INIT(1);
>> +
>> static int of_overlay_apply_one(struct of_overlay *ov,
>> 		struct device_node *target, const struct device_node *overlay);
>> +static int overlay_removal_is_ok(struct of_overlay *ov);
>> 
>> static int of_overlay_apply_single_property(struct of_overlay *ov,
>> 		struct device_node *target, struct property *prop)
>> @@ -339,6 +344,37 @@ void of_overlay_release(struct kobject *kobj)
>> 	kfree(ov);
>> }
>> 
>> +static ssize_t enable_show(struct kobject *kobj,
>> +		struct kobj_attribute *attr, char *buf)
>> +{
>> +	return snprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&ov_enable));
>> +}
>> +
>> +static ssize_t enable_store(struct kobject *kobj,
>> +		struct kobj_attribute *attr, const char *buf, size_t count)
>> +{
>> +	int ret;
>> +	long new_enable;
>> +
>> +	ret = kstrtol(buf, 10, &new_enable);
> 
> strtobool()?

OK

Regards

— Pantelis

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