1 /* 2 * fs/sysfs/dir.c - sysfs core and dir operation implementation 3 * 4 * Copyright (c) 2001-3 Patrick Mochel 5 * Copyright (c) 2007 SUSE Linux Products GmbH 6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de> 7 * 8 * This file is released under the GPLv2. 9 * 10 * Please see Documentation/filesystems/sysfs.txt for more information. 11 */ 12 13 #undef DEBUG 14 15 #include <linux/fs.h> 16 #include <linux/kobject.h> 17 #include <linux/slab.h> 18 #include "sysfs.h" 19 20 DEFINE_SPINLOCK(sysfs_symlink_target_lock); 21 22 /** 23 * sysfs_pathname - return full path to sysfs dirent 24 * @kn: kernfs_node whose path we want 25 * @path: caller allocated buffer of size PATH_MAX 26 * 27 * Gives the name "/" to the sysfs_root entry; any path returned 28 * is relative to wherever sysfs is mounted. 29 */ 30 static char *sysfs_pathname(struct kernfs_node *kn, char *path) 31 { 32 if (kn->parent) { 33 sysfs_pathname(kn->parent, path); 34 strlcat(path, "/", PATH_MAX); 35 } 36 strlcat(path, kn->name, PATH_MAX); 37 return path; 38 } 39 40 void sysfs_warn_dup(struct kernfs_node *parent, const char *name) 41 { 42 char *path; 43 44 path = kzalloc(PATH_MAX, GFP_KERNEL); 45 if (path) { 46 sysfs_pathname(parent, path); 47 strlcat(path, "/", PATH_MAX); 48 strlcat(path, name, PATH_MAX); 49 } 50 51 WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s'\n", 52 path ? path : name); 53 54 kfree(path); 55 } 56 57 /** 58 * sysfs_create_dir_ns - create a directory for an object with a namespace tag 59 * @kobj: object we're creating directory for 60 * @ns: the namespace tag to use 61 */ 62 int sysfs_create_dir_ns(struct kobject *kobj, const void *ns) 63 { 64 struct kernfs_node *parent, *kn; 65 66 BUG_ON(!kobj); 67 68 if (kobj->parent) 69 parent = kobj->parent->sd; 70 else 71 parent = sysfs_root_kn; 72 73 if (!parent) 74 return -ENOENT; 75 76 kn = kernfs_create_dir_ns(parent, kobject_name(kobj), 77 S_IRWXU | S_IRUGO | S_IXUGO, kobj, ns); 78 if (IS_ERR(kn)) { 79 if (PTR_ERR(kn) == -EEXIST) 80 sysfs_warn_dup(parent, kobject_name(kobj)); 81 return PTR_ERR(kn); 82 } 83 84 kobj->sd = kn; 85 return 0; 86 } 87 88 /** 89 * sysfs_remove_dir - remove an object's directory. 90 * @kobj: object. 91 * 92 * The only thing special about this is that we remove any files in 93 * the directory before we remove the directory, and we've inlined 94 * what used to be sysfs_rmdir() below, instead of calling separately. 95 */ 96 void sysfs_remove_dir(struct kobject *kobj) 97 { 98 struct kernfs_node *kn = kobj->sd; 99 100 /* 101 * In general, kboject owner is responsible for ensuring removal 102 * doesn't race with other operations and sysfs doesn't provide any 103 * protection; however, when @kobj is used as a symlink target, the 104 * symlinking entity usually doesn't own @kobj and thus has no 105 * control over removal. @kobj->sd may be removed anytime 106 * and symlink code may end up dereferencing an already freed node. 107 * 108 * sysfs_symlink_target_lock synchronizes @kobj->sd 109 * disassociation against symlink operations so that symlink code 110 * can safely dereference @kobj->sd. 111 */ 112 spin_lock(&sysfs_symlink_target_lock); 113 kobj->sd = NULL; 114 spin_unlock(&sysfs_symlink_target_lock); 115 116 if (kn) { 117 WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR); 118 kernfs_remove(kn); 119 } 120 } 121 122 int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name, 123 const void *new_ns) 124 { 125 struct kernfs_node *parent = kobj->sd->parent; 126 127 return kernfs_rename_ns(kobj->sd, parent, new_name, new_ns); 128 } 129 130 int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj, 131 const void *new_ns) 132 { 133 struct kernfs_node *kn = kobj->sd; 134 struct kernfs_node *new_parent; 135 136 BUG_ON(!kn->parent); 137 new_parent = new_parent_kobj && new_parent_kobj->sd ? 138 new_parent_kobj->sd : sysfs_root_kn; 139 140 return kernfs_rename_ns(kn, new_parent, kn->name, new_ns); 141 } 142