Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754753AbbFLTj2 (ORCPT ); Fri, 12 Jun 2015 15:39:28 -0400 Received: from mail-wi0-f169.google.com ([209.85.212.169]:33389 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753466AbbFLTi3 (ORCPT ); Fri, 12 Jun 2015 15:38:29 -0400 From: Pantelis Antoniou To: Rob Herring Cc: Grant Likely , Andrew Morton , Matt Porter , Koen Kooi , Guenter Roeck , Greg Kroah-Hartman , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Pantelis Antoniou , Pantelis Antoniou Subject: [PATCH v4 2/4] of: overlay: global sysfs enable attribute Date: Fri, 12 Jun 2015 22:38:14 +0300 Message-Id: <1434137896-13806-3-git-send-email-pantelis.antoniou@konsulko.com> X-Mailer: git-send-email 1.7.12 In-Reply-To: <1434137896-13806-1-git-send-email-pantelis.antoniou@konsulko.com> References: <1434137896-13806-1-git-send-email-pantelis.antoniou@konsulko.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2749 Lines: 98 A throw once master enable switch to protect against any further overlay applications if the administrator desires so. Signed-off-by: Pantelis Antoniou --- drivers/of/overlay.c | 43 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-) diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c index f17f5ef..37ec858 100644 --- a/drivers/of/overlay.c +++ b/drivers/of/overlay.c @@ -21,6 +21,7 @@ #include #include #include +#include #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 +344,35 @@ 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)); +} + +static ssize_t enable_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t count) +{ + int ret; + bool new_enable; + + ret = strtobool(buf, &new_enable); + if (ret != 0) + return ret; + /* if we've disabled it, no going back */ + if (atomic_read(&ov_enable) == 0) + return -EPERM; + atomic_set(&ov_enable, (int)new_enable); + return count; +} + +static struct kobj_attribute enable_attr = __ATTR_RW(enable); + +static const struct attribute *overlay_global_attrs[] = { + &enable_attr.attr, + NULL +}; + static struct kobj_type of_overlay_ktype = { .release = of_overlay_release, }; @@ -360,6 +394,10 @@ int of_overlay_create(struct device_node *tree) struct of_overlay *ov; int err, id; + /* administratively disabled */ + if (!atomic_read(&ov_enable)) + return -EPERM; + /* allocate the overlay structure */ ov = kzalloc(sizeof(*ov), GFP_KERNEL); if (ov == NULL) @@ -596,5 +634,8 @@ int of_overlay_init(void) if (!ov_kset) return -ENOMEM; - return 0; + rc = sysfs_create_files(&ov_kset->kobj, overlay_global_attrs); + WARN(rc, "%s: error adding global attributes\n", __func__); + + return rc; } -- 1.7.12 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/