On Thu, Oct 22, 2015 at 10:50:23PM +0300, Pantelis Antoniou wrote:
> A throw once master enable switch to protect against any
> further overlay applications if the administrator desires so.
>
> A kernel command line option is provided as well.
>
> Signed-off-by: Pantelis Antoniou <pantelis.anton...@konsulko.com>
> ---
> drivers/of/overlay.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 49 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index 12c3e47..91f10ed 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 +56,19 @@ 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 __init of_overlay_disable_setup(char *str __always_unused)
> +{
> + atomic_set(&ov_enable, 0);
> + return 1;
> +}
> +__setup("of_overlay_disable", of_overlay_disable_setup);
> +
> 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 +351,35 @@ 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));
Minor nit, you never need to care about the size of the buffer for a
sysfs file, if you do, you are doing something wrong. So this can just
be:
return sprintf(buf, "%d\n", atomic_read(&ov_enable));
Anyway, nothing worth keeping this from being merged:
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
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