kernel/ksysfs.c

   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 #include <linux/kexec.h>
  18
  19 #define KERNEL_ATTR_RO(_name) \
  20 static struct subsys_attribute _name##_attr = __ATTR_RO(_name)
  21
  22 #define KERNEL_ATTR_RW(_name) \
  23 static struct subsys_attribute _name##_attr = \
  24         __ATTR(_name, 0644, _name##_show, _name##_store)
  25
  26 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
  27 /* current uevent sequence number */
  28 static ssize_t uevent_seqnum_show(struct subsystem *subsys, char *page)
  29 {
  30         return sprintf(page, "%llu\n", (unsigned long long)uevent_seqnum);
  31 }
  32 KERNEL_ATTR_RO(uevent_seqnum);
  33
  34 /* uevent helper program, used during early boo */
  35 static ssize_t uevent_helper_show(struct subsystem *subsys, char *page)
  36 {
  37         return sprintf(page, "%s\n", uevent_helper);
  38 }
  39 static ssize_t uevent_helper_store(struct subsystem *subsys, const char *page, size_t count)
  40 {
  41         if (count+1 > UEVENT_HELPER_PATH_LEN)
  42                 return -ENOENT;
  43         memcpy(uevent_helper, page, count);
  44         uevent_helper[count] = '\0';
  45         if (count && uevent_helper[count-1] == '\n')
  46                 uevent_helper[count-1] = '\0';
  47         return count;
  48 }
  49 KERNEL_ATTR_RW(uevent_helper);
  50 #endif
  51
  52 #ifdef CONFIG_KEXEC
  53 static ssize_t kexec_loaded_show(struct subsystem *subsys, char *page)
  54 {
  55         return sprintf(page, "%d\n", !!kexec_image);
  56 }
  57 KERNEL_ATTR_RO(kexec_loaded);
  58
  59 static ssize_t kexec_crash_loaded_show(struct subsystem *subsys, char *page)
  60 {
  61         return sprintf(page, "%d\n", !!kexec_crash_image);
  62 }
  63 KERNEL_ATTR_RO(kexec_crash_loaded);
  64 #endif /* CONFIG_KEXEC */
  65
  66 decl_subsys(kernel, NULL, NULL);
  67 EXPORT_SYMBOL_GPL(kernel_subsys);
  68
  69 static struct attribute * kernel_attrs[] = {
  70 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
  71         &uevent_seqnum_attr.attr,
  72         &uevent_helper_attr.attr,
  73 #endif
  74 #ifdef CONFIG_KEXEC
  75         &kexec_loaded_attr.attr,
  76         &kexec_crash_loaded_attr.attr,
  77 #endif
  78         NULL
  79 };
  80
  81 static struct attribute_group kernel_attr_group = {
  82         .attrs = kernel_attrs,
  83 };
  84
  85 static int __init ksysfs_init(void)
  86 {
  87         int error = subsystem_register(&kernel_subsys);
  88         if (!error)
  89                 error = sysfs_create_group(&kernel_subsys.kset.kobj,
  90                                            &kernel_attr_group);
  91
  92         return error;
  93 }
  94
  95 core_initcall(ksysfs_init);