Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ] 
  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 #include <linux/sched.h>
 18 
 19 #define KERNEL_ATTR_RO(_name) \
 20 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
 21 
 22 #define KERNEL_ATTR_RW(_name) \
 23 static struct kobj_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 kobject *kobj,
 29                                   struct kobj_attribute *attr, char *buf)
 30 {
 31         return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
 32 }
 33 KERNEL_ATTR_RO(uevent_seqnum);
 34 
 35 /* uevent helper program, used during early boo */
 36 static ssize_t uevent_helper_show(struct kobject *kobj,
 37                                   struct kobj_attribute *attr, char *buf)
 38 {
 39         return sprintf(buf, "%s\n", uevent_helper);
 40 }
 41 static ssize_t uevent_helper_store(struct kobject *kobj,
 42                                    struct kobj_attribute *attr,
 43                                    const char *buf, size_t count)
 44 {
 45         if (count+1 > UEVENT_HELPER_PATH_LEN)
 46                 return -ENOENT;
 47         memcpy(uevent_helper, buf, count);
 48         uevent_helper[count] = '\0';
 49         if (count && uevent_helper[count-1] == '\n')
 50                 uevent_helper[count-1] = '\0';
 51         return count;
 52 }
 53 KERNEL_ATTR_RW(uevent_helper);
 54 #endif
 55 
 56 #ifdef CONFIG_KEXEC
 57 static ssize_t kexec_loaded_show(struct kobject *kobj,
 58                                  struct kobj_attribute *attr, char *buf)
 59 {
 60         return sprintf(buf, "%d\n", !!kexec_image);
 61 }
 62 KERNEL_ATTR_RO(kexec_loaded);
 63 
 64 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
 65                                        struct kobj_attribute *attr, char *buf)
 66 {
 67         return sprintf(buf, "%d\n", !!kexec_crash_image);
 68 }
 69 KERNEL_ATTR_RO(kexec_crash_loaded);
 70 
 71 static ssize_t vmcoreinfo_show(struct kobject *kobj,
 72                                struct kobj_attribute *attr, char *buf)
 73 {
 74         return sprintf(buf, "%lx %x\n",
 75                        paddr_vmcoreinfo_note(),
 76                        (unsigned int)vmcoreinfo_max_size);
 77 }
 78 KERNEL_ATTR_RO(vmcoreinfo);
 79 
 80 #endif /* CONFIG_KEXEC */
 81 
 82 /*
 83  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 84  */
 85 extern const void __start_notes __attribute__((weak));
 86 extern const void __stop_notes __attribute__((weak));
 87 #define notes_size (&__stop_notes - &__start_notes)
 88 
 89 static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr,
 90                           char *buf, loff_t off, size_t count)
 91 {
 92         memcpy(buf, &__start_notes + off, count);
 93         return count;
 94 }
 95 
 96 static struct bin_attribute notes_attr = {
 97         .attr = {
 98                 .name = "notes",
 99                 .mode = S_IRUGO,
100         },
101         .read = &notes_read,
102 };
103 
104 struct kobject *kernel_kobj;
105 EXPORT_SYMBOL_GPL(kernel_kobj);
106 
107 static struct attribute * kernel_attrs[] = {
108 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
109         &uevent_seqnum_attr.attr,
110         &uevent_helper_attr.attr,
111 #endif
112 #ifdef CONFIG_KEXEC
113         &kexec_loaded_attr.attr,
114         &kexec_crash_loaded_attr.attr,
115         &vmcoreinfo_attr.attr,
116 #endif
117         NULL
118 };
119 
120 static struct attribute_group kernel_attr_group = {
121         .attrs = kernel_attrs,
122 };
123 
124 static int __init ksysfs_init(void)
125 {
126         int error;
127 
128         kernel_kobj = kobject_create_and_add("kernel", NULL);
129         if (!kernel_kobj) {
130                 error = -ENOMEM;
131                 goto exit;
132         }
133         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
134         if (error)
135                 goto kset_exit;
136 
137         if (notes_size > 0) {
138                 notes_attr.size = notes_size;
139                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
140                 if (error)
141                         goto group_exit;
142         }
143 
144         /* create the /sys/kernel/uids/ directory */
145         error = uids_sysfs_init();
146         if (error)
147                 goto notes_exit;
148 
149         return 0;
150 
151 notes_exit:
152         if (notes_size > 0)
153                 sysfs_remove_bin_file(kernel_kobj, &notes_attr);
154 group_exit:
155         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
156 kset_exit:
157         kobject_put(kernel_kobj);
158 exit:
159         return error;
160 }
161 
162 core_initcall(ksysfs_init);
163
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