1 /* 2 * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which 3 * are not related to any other subsystem 4 * 5 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org> 6 * 7 * This file is release under the GPLv2 8 * 9 */ 10 11 #include <linux/config.h> 12 #include <linux/kobject.h> 13 #include <linux/string.h> 14 #include <linux/sysfs.h> 15 #include <linux/module.h> 16 #include <linux/init.h> 17 18 #define KERNEL_ATTR_RO(_name) \ 19 static struct subsys_attribute _name##_attr = __ATTR_RO(_name) 20 21 #define KERNEL_ATTR_RW(_name) \ 22 static struct subsys_attribute _name##_attr = \ 23 __ATTR(_name, 0644, _name##_show, _name##_store) 24 25 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET) 26 /* current uevent sequence number */ 27 static ssize_t uevent_seqnum_show(struct subsystem *subsys, char *page) 28 { 29 return sprintf(page, "%llu\n", (unsigned long long)uevent_seqnum); 30 } 31 KERNEL_ATTR_RO(uevent_seqnum); 32 33 /* uevent helper program, used during early boo */ 34 static ssize_t uevent_helper_show(struct subsystem *subsys, char *page) 35 { 36 return sprintf(page, "%s\n", uevent_helper); 37 } 38 static ssize_t uevent_helper_store(struct subsystem *subsys, const char *page, size_t count) 39 { 40 if (count+1 > UEVENT_HELPER_PATH_LEN) 41 return -ENOENT; 42 memcpy(uevent_helper, page, count); 43 uevent_helper[count] = '\0'; 44 if (count && uevent_helper[count-1] == '\n') 45 uevent_helper[count-1] = '\0'; 46 return count; 47 } 48 KERNEL_ATTR_RW(uevent_helper); 49 #endif 50 51 decl_subsys(kernel, NULL, NULL); 52 EXPORT_SYMBOL_GPL(kernel_subsys); 53 54 static struct attribute * kernel_attrs[] = { 55 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET) 56 &uevent_seqnum_attr.attr, 57 &uevent_helper_attr.attr, 58 #endif 59 NULL 60 }; 61 62 static struct attribute_group kernel_attr_group = { 63 .attrs = kernel_attrs, 64 }; 65 66 static int __init ksysfs_init(void) 67 { 68 int error = subsystem_register(&kernel_subsys); 69 if (!error) 70 error = sysfs_create_group(&kernel_subsys.kset.kobj, 71 &kernel_attr_group); 72 73 return error; 74 } 75 76 core_initcall(ksysfs_init); 77