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/kobject.h>
  12 #include <linux/string.h>
  13 #include <linux/sysfs.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/kexec.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 kset *kset, 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 kset *kset, char *page)
  35 {
  36         return sprintf(page, "%s\n", uevent_helper);
  37 }
  38 static ssize_t uevent_helper_store(struct kset *kset, 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 #ifdef CONFIG_KEXEC
  52 static ssize_t kexec_loaded_show(struct kset *kset, char *page)
  53 {
  54         return sprintf(page, "%d\n", !!kexec_image);
  55 }
  56 KERNEL_ATTR_RO(kexec_loaded);
  57
  58 static ssize_t kexec_crash_loaded_show(struct kset *kset, char *page)
  59 {
  60         return sprintf(page, "%d\n", !!kexec_crash_image);
  61 }
  62 KERNEL_ATTR_RO(kexec_crash_loaded);
  63 #endif /* CONFIG_KEXEC */
  64
  65 decl_subsys(kernel, NULL, NULL);
  66 EXPORT_SYMBOL_GPL(kernel_subsys);
  67
  68 static struct attribute * kernel_attrs[] = {
  69 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
  70         &uevent_seqnum_attr.attr,
  71         &uevent_helper_attr.attr,
  72 #endif
  73 #ifdef CONFIG_KEXEC
  74         &kexec_loaded_attr.attr,
  75         &kexec_crash_loaded_attr.attr,
  76 #endif
  77         NULL
  78 };
  79
  80 static struct attribute_group kernel_attr_group = {
  81         .attrs = kernel_attrs,
  82 };
  83
  84 static int __init ksysfs_init(void)
  85 {
  86         int error = subsystem_register(&kernel_subsys);
  87         if (!error)
  88                 error = sysfs_create_group(&kernel_subsys.kobj,
  89                                            &kernel_attr_group);
  90
  91         return error;
  92 }
  93
  94 core_initcall(ksysfs_init);