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

Hi Greg,

On Apr 24, 2015, at 23:36 , Greg KH [off-list ref] wrote:

On Fri, Apr 24, 2015 at 12:45:42PM +0300, Pantelis Antoniou wrote:

quoted

A throw once master enable switch to protect against any
further overlay applications if the administrator desires so.

Signed-off-by: Pantelis Antoniou <redacted>
---
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