1 files changed, 26 insertions, 4 deletions

diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 015fb69ad94d..99af8b05eeaa 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -15,6 +15,9 @@
 #include <linux/module.h>
 #include <linux/init.h>
 
+u64 uevent_seqnum;
+char uevent_helper[UEVENT_HELPER_PATH_LEN] = "/sbin/hotplug";
+
 #define KERNEL_ATTR_RO(_name) \
 static struct subsys_attribute _name##_attr = __ATTR_RO(_name)
 
@@ -23,11 +26,29 @@ static struct subsys_attribute _name##_attr = \
         __ATTR(_name, 0644, _name##_show, _name##_store)
 
 #ifdef CONFIG_HOTPLUG
-static ssize_t hotplug_seqnum_show(struct subsystem *subsys, char *page)
+/* current uevent sequence number */
+static ssize_t uevent_seqnum_show(struct subsystem *subsys, char *page)
+{
+        return sprintf(page, "%llu\n", (unsigned long long)uevent_seqnum);
+}
+KERNEL_ATTR_RO(uevent_seqnum);
+
+/* uevent helper program, used during early boo */
+static ssize_t uevent_helper_show(struct subsystem *subsys, char *page)
+{
+        return sprintf(page, "%s\n", uevent_helper);
+}
+static ssize_t uevent_helper_store(struct subsystem *subsys, const char *page, size_t count)
 {
-        return sprintf(page, "%llu\n", (unsigned long long)hotplug_seqnum);
+        if (count+1 > UEVENT_HELPER_PATH_LEN)
+                return -ENOENT;
+        memcpy(uevent_helper, page, count);
+        uevent_helper[count] = '\0';
+        if (count && uevent_helper[count-1] == '\n')
+                uevent_helper[count-1] = '\0';
+        return count;
 }
-KERNEL_ATTR_RO(hotplug_seqnum);
+KERNEL_ATTR_RW(uevent_helper);
 #endif
 
 #ifdef CONFIG_KEXEC
@@ -45,7 +66,8 @@ EXPORT_SYMBOL_GPL(kernel_subsys);
 
 static struct attribute * kernel_attrs[] = {
 #ifdef CONFIG_HOTPLUG
-        &hotplug_seqnum_attr.attr,
+        &uevent_seqnum_attr.attr,
+        &uevent_helper_attr.attr,
 #endif
 #ifdef CONFIG_KEXEC
         &crash_notes_attr.attr,