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authorTejun Heo <tj@kernel.org>2014-02-07 22:32:07 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-08 04:05:35 +0400
commit3eef34ad7dc369b7183ec383908aff3da2f6e5ec (patch)
treefac6ef1dd497adeff55fae499d953d5d51061867 /fs/sysfs/dir.c
parent0c23b2259a4850494e2c53e864ea840597c6cdd3 (diff)
downloadlinux-3eef34ad7dc369b7183ec383908aff3da2f6e5ec.tar.xz
kernfs: implement kernfs_get_parent(), kernfs_name/path() and friends
kernfs_node->parent and ->name are currently marked as "published" indicating that kernfs users may access them directly; however, those fields may get updated by kernfs_rename[_ns]() and unrestricted access may lead to erroneous values or oops. Protect ->parent and ->name updates with a irq-safe spinlock kernfs_rename_lock and implement the following accessors for these fields. * kernfs_name() - format the node's name into the specified buffer * kernfs_path() - format the node's path into the specified buffer * pr_cont_kernfs_name() - pr_cont a node's name (doesn't need buffer) * pr_cont_kernfs_path() - pr_cont a node's path (doesn't need buffer) * kernfs_get_parent() - pin and return a node's parent All can be called under any context. The recursive sysfs_pathname() in fs/sysfs/dir.c is replaced with kernfs_path() and sysfs_rename_dir_ns() is updated to use kernfs_get_parent() instead of dereferencing parent directly. v2: Dummy definition of kernfs_path() for !CONFIG_KERNFS was missing static inline making it cause a lot of build warnings. Add it. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/sysfs/dir.c')
-rw-r--r--fs/sysfs/dir.c44
1 files changed, 13 insertions, 31 deletions
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index ee0d761c3179..0b45ff42f374 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -19,39 +19,18 @@
DEFINE_SPINLOCK(sysfs_symlink_target_lock);
-/**
- * sysfs_pathname - return full path to sysfs dirent
- * @kn: kernfs_node whose path we want
- * @path: caller allocated buffer of size PATH_MAX
- *
- * Gives the name "/" to the sysfs_root entry; any path returned
- * is relative to wherever sysfs is mounted.
- */
-static char *sysfs_pathname(struct kernfs_node *kn, char *path)
-{
- if (kn->parent) {
- sysfs_pathname(kn->parent, path);
- strlcat(path, "/", PATH_MAX);
- }
- strlcat(path, kn->name, PATH_MAX);
- return path;
-}
-
void sysfs_warn_dup(struct kernfs_node *parent, const char *name)
{
- char *path;
+ char *buf, *path = NULL;
- path = kzalloc(PATH_MAX, GFP_KERNEL);
- if (path) {
- sysfs_pathname(parent, path);
- strlcat(path, "/", PATH_MAX);
- strlcat(path, name, PATH_MAX);
- }
+ buf = kzalloc(PATH_MAX, GFP_KERNEL);
+ if (buf)
+ path = kernfs_path(parent, buf, PATH_MAX);
- WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s'\n",
- path ? path : name);
+ WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s/%s'\n",
+ path, name);
- kfree(path);
+ kfree(buf);
}
/**
@@ -122,9 +101,13 @@ void sysfs_remove_dir(struct kobject *kobj)
int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
const void *new_ns)
{
- struct kernfs_node *parent = kobj->sd->parent;
+ struct kernfs_node *parent;
+ int ret;
- return kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
+ parent = kernfs_get_parent(kobj->sd);
+ ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
+ kernfs_put(parent);
+ return ret;
}
int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
@@ -133,7 +116,6 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
struct kernfs_node *kn = kobj->sd;
struct kernfs_node *new_parent;
- BUG_ON(!kn->parent);
new_parent = new_parent_kobj && new_parent_kobj->sd ?
new_parent_kobj->sd : sysfs_root_kn;