Merge git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl

Pull sysctl updates from Eric Biederman:

 - Rewrite of sysctl for speed and clarity.

   Insert/remove/Lookup in sysctl are all now O(NlogN) operations, and
   are no longer bottlenecks in the process of adding and removing
   network devices.

   sysctl is now focused on being a filesystem instead of system call
   and the code can all be found in fs/proc/proc_sysctl.c.  Hopefully
   this means the code is now approachable.

   Much thanks is owed to Lucian Grinjincu for keeping at this until
   something was found that was usable.

 - The recent proc_sys_poll oops found by the fuzzer during hibernation
   is fixed.

* git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl: (36 commits)
  sysctl: protect poll() in entries that may go away
  sysctl: Don't call sysctl_follow_link unless we are a link.
  sysctl: Comments to make the code clearer.
  sysctl: Correct error return from get_subdir
  sysctl: An easier to read version of find_subdir
  sysctl: fix memset parameters in setup_sysctl_set()
  sysctl: remove an unused variable
  sysctl: Add register_sysctl for normal sysctl users
  sysctl: Index sysctl directories with rbtrees.
  sysctl: Make the header lists per directory.
  sysctl: Move sysctl_check_dups into insert_header
  sysctl: Modify __register_sysctl_paths to take a set instead of a root and an nsproxy
  sysctl: Replace root_list with links between sysctl_table_sets.
  sysctl: Add sysctl_print_dir and use it in get_subdir
  sysctl: Stop requiring explicit management of sysctl directories
  sysctl: Add a root pointer to ctl_table_set
  sysctl: Rewrite proc_sys_readdir in terms of first_entry and next_entry
  sysctl: Rewrite proc_sys_lookup introducing find_entry and lookup_entry.
  sysctl: Normalize the root_table data structure.
  sysctl: Factor out insert_header and erase_header
  ...

2 files changed, 1201 insertions, 76 deletions

diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index c44efe19798f..5f79bb8b4c60 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -10,12 +10,15 @@
  */
 
 #include <linux/proc_fs.h>
+struct  ctl_table_header;
 
 extern struct proc_dir_entry proc_root;
 #ifdef CONFIG_PROC_SYSCTL
 extern int proc_sys_init(void);
+extern void sysctl_head_put(struct ctl_table_header *head);
 #else
 static inline void proc_sys_init(void) { }
+static inline void sysctl_head_put(struct ctl_table_header *head) { }
 #endif
 #ifdef CONFIG_NET
 extern int proc_net_init(void);
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 67bbf6e4e197..21d836f40292 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -9,6 +9,7 @@
 #include <linux/sched.h>
 #include <linux/namei.h>
 #include <linux/mm.h>
+#include <linux/module.h>
 #include "internal.h"
 
 static const struct dentry_operations proc_sys_dentry_operations;
@@ -26,6 +27,371 @@ void proc_sys_poll_notify(struct ctl_table_poll *poll)
         wake_up_interruptible(&poll->wait);
 }
 
+static struct ctl_table root_table[] = {
+        {
+                .procname = "",
+                .mode = S_IFDIR|S_IRUGO|S_IXUGO,
+        },
+        { }
+};
+static struct ctl_table_root sysctl_table_root = {
+        .default_set.dir.header = {
+                {{.count = 1,
+                  .nreg = 1,
+                  .ctl_table = root_table }},
+                .ctl_table_arg = root_table,
+                .root = &sysctl_table_root,
+                .set = &sysctl_table_root.default_set,
+        },
+};
+
+static DEFINE_SPINLOCK(sysctl_lock);
+
+static void drop_sysctl_table(struct ctl_table_header *header);
+static int sysctl_follow_link(struct ctl_table_header **phead,
+        struct ctl_table **pentry, struct nsproxy *namespaces);
+static int insert_links(struct ctl_table_header *head);
+static void put_links(struct ctl_table_header *header);
+
+static void sysctl_print_dir(struct ctl_dir *dir)
+{
+        if (dir->header.parent)
+                sysctl_print_dir(dir->header.parent);
+        printk(KERN_CONT "%s/", dir->header.ctl_table[0].procname);
+}
+
+static int namecmp(const char *name1, int len1, const char *name2, int len2)
+{
+        int minlen;
+        int cmp;
+
+        minlen = len1;
+        if (minlen > len2)
+                minlen = len2;
+
+        cmp = memcmp(name1, name2, minlen);
+        if (cmp == 0)
+                cmp = len1 - len2;
+        return cmp;
+}
+
+/* Called under sysctl_lock */
+static struct ctl_table *find_entry(struct ctl_table_header **phead,
+        struct ctl_dir *dir, const char *name, int namelen)
+{
+        struct ctl_table_header *head;
+        struct ctl_table *entry;
+        struct rb_node *node = dir->root.rb_node;
+
+        while (node)
+        {
+                struct ctl_node *ctl_node;
+                const char *procname;
+                int cmp;
+
+                ctl_node = rb_entry(node, struct ctl_node, node);
+                head = ctl_node->header;
+                entry = &head->ctl_table[ctl_node - head->node];
+                procname = entry->procname;
+
+                cmp = namecmp(name, namelen, procname, strlen(procname));
+                if (cmp < 0)
+                        node = node->rb_left;
+                else if (cmp > 0)
+                        node = node->rb_right;
+                else {
+                        *phead = head;
+                        return entry;
+                }
+        }
+        return NULL;
+}
+
+static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
+{
+        struct rb_node *node = &head->node[entry - head->ctl_table].node;
+        struct rb_node **p = &head->parent->root.rb_node;
+        struct rb_node *parent = NULL;
+        const char *name = entry->procname;
+        int namelen = strlen(name);
+
+        while (*p) {
+                struct ctl_table_header *parent_head;
+                struct ctl_table *parent_entry;
+                struct ctl_node *parent_node;
+                const char *parent_name;
+                int cmp;
+
+                parent = *p;
+                parent_node = rb_entry(parent, struct ctl_node, node);
+                parent_head = parent_node->header;
+                parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
+                parent_name = parent_entry->procname;
+
+                cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
+                if (cmp < 0)
+                        p = &(*p)->rb_left;
+                else if (cmp > 0)
+                        p = &(*p)->rb_right;
+                else {
+                        printk(KERN_ERR "sysctl duplicate entry: ");
+                        sysctl_print_dir(head->parent);
+                        printk(KERN_CONT "/%s\n", entry->procname);
+                        return -EEXIST;
+                }
+        }
+
+        rb_link_node(node, parent, p);
+        return 0;
+}
+
+static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
+{
+        struct rb_node *node = &head->node[entry - head->ctl_table].node;
+
+        rb_erase(node, &head->parent->root);
+}
+
+static void init_header(struct ctl_table_header *head,
+        struct ctl_table_root *root, struct ctl_table_set *set,
+        struct ctl_node *node, struct ctl_table *table)
+{
+        head->ctl_table = table;
+        head->ctl_table_arg = table;
+        head->used = 0;
+        head->count = 1;
+        head->nreg = 1;
+        head->unregistering = NULL;
+        head->root = root;
+        head->set = set;
+        head->parent = NULL;
+        head->node = node;
+        if (node) {
+                struct ctl_table *entry;
+                for (entry = table; entry->procname; entry++, node++) {
+                        rb_init_node(&node->node);
+                        node->header = head;
+                }
+        }
+}
+
+static void erase_header(struct ctl_table_header *head)
+{
+        struct ctl_table *entry;
+        for (entry = head->ctl_table; entry->procname; entry++)
+                erase_entry(head, entry);
+}
+
+static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
+{
+        struct ctl_table *entry;
+        int err;
+
+        dir->header.nreg++;
+        header->parent = dir;
+        err = insert_links(header);
+        if (err)
+                goto fail_links;
+        for (entry = header->ctl_table; entry->procname; entry++) {
+                err = insert_entry(header, entry);
+                if (err)
+                        goto fail;
+        }
+        return 0;
+fail:
+        erase_header(header);
+        put_links(header);
+fail_links:
+        header->parent = NULL;
+        drop_sysctl_table(&dir->header);
+        return err;
+}
+
+/* called under sysctl_lock */
+static int use_table(struct ctl_table_header *p)
+{
+        if (unlikely(p->unregistering))
+                return 0;
+        p->used++;
+        return 1;
+}
+
+/* called under sysctl_lock */
+static void unuse_table(struct ctl_table_header *p)
+{
+        if (!--p->used)
+                if (unlikely(p->unregistering))
+                        complete(p->unregistering);
+}
+
+/* called under sysctl_lock, will reacquire if has to wait */
+static void start_unregistering(struct ctl_table_header *p)
+{
+        /*
+         * if p->used is 0, nobody will ever touch that entry again;
+         * we'll eliminate all paths to it before dropping sysctl_lock
+         */
+        if (unlikely(p->used)) {
+                struct completion wait;
+                init_completion(&wait);
+                p->unregistering = &wait;
+                spin_unlock(&sysctl_lock);
+                wait_for_completion(&wait);
+                spin_lock(&sysctl_lock);
+        } else {
+                /* anything non-NULL; we'll never dereference it */
+                p->unregistering = ERR_PTR(-EINVAL);
+        }
+        /*
+         * do not remove from the list until nobody holds it; walking the
+         * list in do_sysctl() relies on that.
+         */
+        erase_header(p);
+}
+
+static void sysctl_head_get(struct ctl_table_header *head)
+{
+        spin_lock(&sysctl_lock);
+        head->count++;
+        spin_unlock(&sysctl_lock);
+}
+
+void sysctl_head_put(struct ctl_table_header *head)
+{
+        spin_lock(&sysctl_lock);
+        if (!--head->count)
+                kfree_rcu(head, rcu);
+        spin_unlock(&sysctl_lock);
+}
+
+static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
+{
+        if (!head)
+                BUG();
+        spin_lock(&sysctl_lock);
+        if (!use_table(head))
+                head = ERR_PTR(-ENOENT);
+        spin_unlock(&sysctl_lock);
+        return head;
+}
+
+static void sysctl_head_finish(struct ctl_table_header *head)
+{
+        if (!head)
+                return;
+        spin_lock(&sysctl_lock);
+        unuse_table(head);
+        spin_unlock(&sysctl_lock);
+}
+
+static struct ctl_table_set *
+lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
+{
+        struct ctl_table_set *set = &root->default_set;
+        if (root->lookup)
+                set = root->lookup(root, namespaces);
+        return set;
+}
+
+static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
+                                      struct ctl_dir *dir,
+                                      const char *name, int namelen)
+{
+        struct ctl_table_header *head;
+        struct ctl_table *entry;
+
+        spin_lock(&sysctl_lock);
+        entry = find_entry(&head, dir, name, namelen);
+        if (entry && use_table(head))
+                *phead = head;
+        else
+                entry = NULL;
+        spin_unlock(&sysctl_lock);
+        return entry;
+}
+
+static struct ctl_node *first_usable_entry(struct rb_node *node)
+{
+        struct ctl_node *ctl_node;
+
+        for (;node; node = rb_next(node)) {
+                ctl_node = rb_entry(node, struct ctl_node, node);
+                if (use_table(ctl_node->header))
+                        return ctl_node;
+        }
+        return NULL;
+}
+
+static void first_entry(struct ctl_dir *dir,
+        struct ctl_table_header **phead, struct ctl_table **pentry)
+{
+        struct ctl_table_header *head = NULL;
+        struct ctl_table *entry = NULL;
+        struct ctl_node *ctl_node;
+
+        spin_lock(&sysctl_lock);
+        ctl_node = first_usable_entry(rb_first(&dir->root));
+        spin_unlock(&sysctl_lock);
+        if (ctl_node) {
+                head = ctl_node->header;
+                entry = &head->ctl_table[ctl_node - head->node];
+        }
+        *phead = head;
+        *pentry = entry;
+}
+
+static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
+{
+        struct ctl_table_header *head = *phead;
+        struct ctl_table *entry = *pentry;
+        struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
+
+        spin_lock(&sysctl_lock);
+        unuse_table(head);
+
+        ctl_node = first_usable_entry(rb_next(&ctl_node->node));
+        spin_unlock(&sysctl_lock);
+        head = NULL;
+        if (ctl_node) {
+                head = ctl_node->header;
+                entry = &head->ctl_table[ctl_node - head->node];
+        }
+        *phead = head;
+        *pentry = entry;
+}
+
+void register_sysctl_root(struct ctl_table_root *root)
+{
+}
+
+/*
+ * sysctl_perm does NOT grant the superuser all rights automatically, because
+ * some sysctl variables are readonly even to root.
+ */
+
+static int test_perm(int mode, int op)
+{
+        if (!current_euid())
+                mode >>= 6;
+        else if (in_egroup_p(0))
+                mode >>= 3;
+        if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
+                return 0;
+        return -EACCES;
+}
+
+static int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
+{
+        int mode;
+
+        if (root->permissions)
+                mode = root->permissions(root, current->nsproxy, table);
+        else
+                mode = table->mode;
+
+        return test_perm(mode, op);
+}
+
 static struct inode *proc_sys_make_inode(struct super_block *sb,
                 struct ctl_table_header *head, struct ctl_table *table)
 {
@@ -45,13 +411,12 @@ static struct inode *proc_sys_make_inode(struct super_block *sb,
 
         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
         inode->i_mode = table->mode;
-        if (!table->child) {
+        if (!S_ISDIR(table->mode)) {
                 inode->i_mode |= S_IFREG;
                 inode->i_op = &proc_sys_inode_operations;
                 inode->i_fop = &proc_sys_file_operations;
         } else {
                 inode->i_mode |= S_IFDIR;
-                clear_nlink(inode);
                 inode->i_op = &proc_sys_dir_operations;
                 inode->i_fop = &proc_sys_dir_file_operations;
         }
@@ -59,70 +424,42 @@ out:
         return inode;
 }
 
-static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name)
-{
-        int len;
-        for ( ; p->procname; p++) {
-
-                if (!p->procname)
-                        continue;
-
-                len = strlen(p->procname);
-                if (len != name->len)
-                        continue;
-
-                if (memcmp(p->procname, name->name, len) != 0)
-                        continue;
-
-                /* I have a match */
-                return p;
-        }
-        return NULL;
-}
-
 static struct ctl_table_header *grab_header(struct inode *inode)
 {
-        if (PROC_I(inode)->sysctl)
-                return sysctl_head_grab(PROC_I(inode)->sysctl);
-        else
-                return sysctl_head_next(NULL);
+        struct ctl_table_header *head = PROC_I(inode)->sysctl;
+        if (!head)
+                head = &sysctl_table_root.default_set.dir.header;
+        return sysctl_head_grab(head);
 }
 
 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
                                         struct nameidata *nd)
 {
         struct ctl_table_header *head = grab_header(dir);
-        struct ctl_table *table = PROC_I(dir)->sysctl_entry;
         struct ctl_table_header *h = NULL;
         struct qstr *name = &dentry->d_name;
         struct ctl_table *p;
         struct inode *inode;
         struct dentry *err = ERR_PTR(-ENOENT);
+        struct ctl_dir *ctl_dir;
+        int ret;
 
         if (IS_ERR(head))
                 return ERR_CAST(head);
 
-        if (table && !table->child) {
-                WARN_ON(1);
-                goto out;
-        }
-
-        table = table ? table->child : head->ctl_table;
-
-        p = find_in_table(table, name);
-        if (!p) {
-                for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
-                        if (h->attached_to != table)
-                                continue;
-                        p = find_in_table(h->attached_by, name);
-                        if (p)
-                                break;
-                }
-        }
+        ctl_dir = container_of(head, struct ctl_dir, header);
 
+        p = lookup_entry(&h, ctl_dir, name->name, name->len);
         if (!p)
                 goto out;
 
+        if (S_ISLNK(p->mode)) {
+                ret = sysctl_follow_link(&h, &p, current->nsproxy);
+                err = ERR_PTR(ret);
+                if (ret)
+                        goto out;
+        }
+
         err = ERR_PTR(-ENOMEM);
         inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
         if (h)
@@ -190,20 +527,32 @@ static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
 
 static int proc_sys_open(struct inode *inode, struct file *filp)
 {
+        struct ctl_table_header *head = grab_header(inode);
         struct ctl_table *table = PROC_I(inode)->sysctl_entry;
 
+        /* sysctl was unregistered */
+        if (IS_ERR(head))
+                return PTR_ERR(head);
+
         if (table->poll)
                 filp->private_data = proc_sys_poll_event(table->poll);
 
+        sysctl_head_finish(head);
+
         return 0;
 }
 
 static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
 {
         struct inode *inode = filp->f_path.dentry->d_inode;
+        struct ctl_table_header *head = grab_header(inode);
         struct ctl_table *table = PROC_I(inode)->sysctl_entry;
-        unsigned long event = (unsigned long)filp->private_data;
         unsigned int ret = DEFAULT_POLLMASK;
+        unsigned long event;
+
+        /* sysctl was unregistered */
+        if (IS_ERR(head))
+                return POLLERR | POLLHUP;
 
         if (!table->proc_handler)
                 goto out;
@@ -211,6 +560,7 @@ static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
         if (!table->poll)
                 goto out;
 
+        event = (unsigned long)filp->private_data;
         poll_wait(filp, &table->poll->wait, wait);
 
         if (event != atomic_read(&table->poll->event)) {
@@ -219,6 +569,8 @@ static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
         }
 
 out:
+        sysctl_head_finish(head);
+
         return ret;
 }
 
@@ -260,28 +612,45 @@ static int proc_sys_fill_cache(struct file *filp, void *dirent,
         return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
 }
 
+static int proc_sys_link_fill_cache(struct file *filp, void *dirent,
+                                    filldir_t filldir,
+                                    struct ctl_table_header *head,
+                                    struct ctl_table *table)
+{
+        int err, ret = 0;
+        head = sysctl_head_grab(head);
+
+        if (S_ISLNK(table->mode)) {
+                /* It is not an error if we can not follow the link ignore it */
+                err = sysctl_follow_link(&head, &table, current->nsproxy);
+                if (err)
+                        goto out;
+        }
+
+        ret = proc_sys_fill_cache(filp, dirent, filldir, head, table);
+out:
+        sysctl_head_finish(head);
+        return ret;
+}
+
 static int scan(struct ctl_table_header *head, ctl_table *table,
                 unsigned long *pos, struct file *file,
                 void *dirent, filldir_t filldir)
 {
+        int res;
 
-        for (; table->procname; table++, (*pos)++) {
-                int res;
-
-                /* Can't do anything without a proc name */
-                if (!table->procname)
-                        continue;
-
-                if (*pos < file->f_pos)
-                        continue;
+        if ((*pos)++ < file->f_pos)
+                return 0;
 
+        if (unlikely(S_ISLNK(table->mode)))
+                res = proc_sys_link_fill_cache(file, dirent, filldir, head, table);
+        else
                 res = proc_sys_fill_cache(file, dirent, filldir, head, table);
-                if (res)
-                        return res;
 
-                file->f_pos = *pos + 1;
-        }
-        return 0;
+        if (res == 0)
+                file->f_pos = *pos;
+
+        return res;
 }
 
 static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
@@ -289,20 +658,16 @@ static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
         struct dentry *dentry = filp->f_path.dentry;
         struct inode *inode = dentry->d_inode;
         struct ctl_table_header *head = grab_header(inode);
-        struct ctl_table *table = PROC_I(inode)->sysctl_entry;
         struct ctl_table_header *h = NULL;
+        struct ctl_table *entry;
+        struct ctl_dir *ctl_dir;
         unsigned long pos;
         int ret = -EINVAL;
 
         if (IS_ERR(head))
                 return PTR_ERR(head);
 
-        if (table && !table->child) {
-                WARN_ON(1);
-                goto out;
-        }
-
-        table = table ? table->child : head->ctl_table;
+        ctl_dir = container_of(head, struct ctl_dir, header);
 
         ret = 0;
         /* Avoid a switch here: arm builds fail with missing __cmpdi2 */
@@ -320,14 +685,8 @@ static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
         }
         pos = 2;
 
-        ret = scan(head, table, &pos, filp, dirent, filldir);
-        if (ret)
-                goto out;
-
-        for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
-                if (h->attached_to != table)
-                        continue;
-                ret = scan(h, h->attached_by, &pos, filp, dirent, filldir);
+        for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
+                ret = scan(h, entry, &pos, filp, dirent, filldir);
                 if (ret) {
                         sysctl_head_finish(h);
                         break;
@@ -447,6 +806,21 @@ static int proc_sys_delete(const struct dentry *dentry)
         return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
 }
 
+static int sysctl_is_seen(struct ctl_table_header *p)
+{
+        struct ctl_table_set *set = p->set;
+        int res;
+        spin_lock(&sysctl_lock);
+        if (p->unregistering)
+                res = 0;
+        else if (!set->is_seen)
+                res = 1;
+        else
+                res = set->is_seen(set);
+        spin_unlock(&sysctl_lock);
+        return res;
+}
+
 static int proc_sys_compare(const struct dentry *parent,
                 const struct inode *pinode,
                 const struct dentry *dentry, const struct inode *inode,
@@ -472,6 +846,753 @@ static const struct dentry_operations proc_sys_dentry_operations = {
         .d_compare      = proc_sys_compare,
 };
 
+static struct ctl_dir *find_subdir(struct ctl_dir *dir,
+                                   const char *name, int namelen)
+{
+        struct ctl_table_header *head;
+        struct ctl_table *entry;
+
+        entry = find_entry(&head, dir, name, namelen);
+        if (!entry)
+                return ERR_PTR(-ENOENT);
+        if (!S_ISDIR(entry->mode))
+                return ERR_PTR(-ENOTDIR);
+        return container_of(head, struct ctl_dir, header);
+}
+
+static struct ctl_dir *new_dir(struct ctl_table_set *set,
+                               const char *name, int namelen)
+{
+        struct ctl_table *table;
+        struct ctl_dir *new;
+        struct ctl_node *node;
+        char *new_name;
+
+        new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
+                      sizeof(struct ctl_table)*2 +  namelen + 1,
+                      GFP_KERNEL);
+        if (!new)
+                return NULL;
+
+        node = (struct ctl_node *)(new + 1);
+        table = (struct ctl_table *)(node + 1);
+        new_name = (char *)(table + 2);
+        memcpy(new_name, name, namelen);
+        new_name[namelen] = '\0';
+        table[0].procname = new_name;
+        table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
+        init_header(&new->header, set->dir.header.root, set, node, table);
+
+        return new;
+}
+
+/**
+ * get_subdir - find or create a subdir with the specified name.
+ * @dir:  Directory to create the subdirectory in
+ * @name: The name of the subdirectory to find or create
+ * @namelen: The length of name
+ *
+ * Takes a directory with an elevated reference count so we know that
+ * if we drop the lock the directory will not go away.  Upon success
+ * the reference is moved from @dir to the returned subdirectory.
+ * Upon error an error code is returned and the reference on @dir is
+ * simply dropped.
+ */
+static struct ctl_dir *get_subdir(struct ctl_dir *dir,
+                                  const char *name, int namelen)
+{
+        struct ctl_table_set *set = dir->header.set;
+        struct ctl_dir *subdir, *new = NULL;
+        int err;
+
+        spin_lock(&sysctl_lock);
+        subdir = find_subdir(dir, name, namelen);
+        if (!IS_ERR(subdir))
+                goto found;
+        if (PTR_ERR(subdir) != -ENOENT)
+                goto failed;
+
+        spin_unlock(&sysctl_lock);
+        new = new_dir(set, name, namelen);
+        spin_lock(&sysctl_lock);
+        subdir = ERR_PTR(-ENOMEM);
+        if (!new)
+                goto failed;
+
+        /* Was the subdir added while we dropped the lock? */
+        subdir = find_subdir(dir, name, namelen);
+        if (!IS_ERR(subdir))
+                goto found;
+        if (PTR_ERR(subdir) != -ENOENT)
+                goto failed;
+
+        /* Nope.  Use the our freshly made directory entry. */
+        err = insert_header(dir, &new->header);
+        subdir = ERR_PTR(err);
+        if (err)
+                goto failed;
+        subdir = new;
+found:
+        subdir->header.nreg++;
+failed:
+        if (unlikely(IS_ERR(subdir))) {
+                printk(KERN_ERR "sysctl could not get directory: ");
+                sysctl_print_dir(dir);
+                printk(KERN_CONT "/%*.*s %ld\n",
+                        namelen, namelen, name, PTR_ERR(subdir));
+        }
+        drop_sysctl_table(&dir->header);
+        if (new)
+                drop_sysctl_table(&new->header);
+        spin_unlock(&sysctl_lock);
+        return subdir;
+}
+
+static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
+{
+        struct ctl_dir *parent;
+        const char *procname;
+        if (!dir->header.parent)
+                return &set->dir;
+        parent = xlate_dir(set, dir->header.parent);
+        if (IS_ERR(parent))
+                return parent;
+        procname = dir->header.ctl_table[0].procname;
+        return find_subdir(parent, procname, strlen(procname));
+}
+
+static int sysctl_follow_link(struct ctl_table_header **phead,
+        struct ctl_table **pentry, struct nsproxy *namespaces)
+{
+        struct ctl_table_header *head;
+        struct ctl_table_root *root;
+        struct ctl_table_set *set;
+        struct ctl_table *entry;
+        struct ctl_dir *dir;
+        int ret;
+
+        ret = 0;
+        spin_lock(&sysctl_lock);
+        root = (*pentry)->data;
+        set = lookup_header_set(root, namespaces);
+        dir = xlate_dir(set, (*phead)->parent);
+        if (IS_ERR(dir))
+                ret = PTR_ERR(dir);
+        else {
+                const char *procname = (*pentry)->procname;
+                head = NULL;
+                entry = find_entry(&head, dir, procname, strlen(procname));
+                ret = -ENOENT;
+                if (entry && use_table(head)) {
+                        unuse_table(*phead);
+                        *phead = head;
+                        *pentry = entry;
+                        ret = 0;
+                }
+        }
+
+        spin_unlock(&sysctl_lock);
+        return ret;
+}
+
+static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
+{
+        struct va_format vaf;
+        va_list args;
+
+        va_start(args, fmt);
+        vaf.fmt = fmt;
+        vaf.va = &args;
+
+        printk(KERN_ERR "sysctl table check failed: %s/%s %pV\n",
+                path, table->procname, &vaf);
+
+        va_end(args);
+        return -EINVAL;
+}
+
+static int sysctl_check_table(const char *path, struct ctl_table *table)
+{
+        int err = 0;
+        for (; table->procname; table++) {
+                if (table->child)
+                        err = sysctl_err(path, table, "Not a file");
+
+                if ((table->proc_handler == proc_dostring) ||
+                    (table->proc_handler == proc_dointvec) ||
+                    (table->proc_handler == proc_dointvec_minmax) ||
+                    (table->proc_handler == proc_dointvec_jiffies) ||
+                    (table->proc_handler == proc_dointvec_userhz_jiffies) ||
+                    (table->proc_handler == proc_dointvec_ms_jiffies) ||
+                    (table->proc_handler == proc_doulongvec_minmax) ||
+                    (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
+                        if (!table->data)
+                                err = sysctl_err(path, table, "No data");
+                        if (!table->maxlen)
+                                err = sysctl_err(path, table, "No maxlen");
+                }
+                if (!table->proc_handler)
+                        err = sysctl_err(path, table, "No proc_handler");
+
+                if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
+                        err = sysctl_err(path, table, "bogus .mode 0%o",
+                                table->mode);
+        }
+        return err;
+}
+
+static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
+        struct ctl_table_root *link_root)
+{
+        struct ctl_table *link_table, *entry, *link;
+        struct ctl_table_header *links;
+        struct ctl_node *node;
+        char *link_name;
+        int nr_entries, name_bytes;
+
+        name_bytes = 0;
+        nr_entries = 0;
+        for (entry = table; entry->procname; entry++) {
+                nr_entries++;
+                name_bytes += strlen(entry->procname) + 1;
+        }
+
+        links = kzalloc(sizeof(struct ctl_table_header) +
+                        sizeof(struct ctl_node)*nr_entries +
+                        sizeof(struct ctl_table)*(nr_entries + 1) +
+                        name_bytes,
+                        GFP_KERNEL);
+
+        if (!links)
+                return NULL;
+
+        node = (struct ctl_node *)(links + 1);
+        link_table = (struct ctl_table *)(node + nr_entries);
+        link_name = (char *)&link_table[nr_entries + 1];
+
+        for (link = link_table, entry = table; entry->procname; link++, entry++) {
+                int len = strlen(entry->procname) + 1;
+                memcpy(link_name, entry->procname, len);
+                link->procname = link_name;
+                link->mode = S_IFLNK|S_IRWXUGO;
+                link->data = link_root;
+                link_name += len;
+        }
+        init_header(links, dir->header.root, dir->header.set, node, link_table);
+        links->nreg = nr_entries;
+
+        return links;
+}
+
+static bool get_links(struct ctl_dir *dir,
+        struct ctl_table *table, struct ctl_table_root *link_root)
+{
+        struct ctl_table_header *head;
+        struct ctl_table *entry, *link;
+
+        /* Are there links available for every entry in table? */
+        for (entry = table; entry->procname; entry++) {
+                const char *procname = entry->procname;
+                link = find_entry(&head, dir, procname, strlen(procname));
+                if (!link)
+                        return false;
+                if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
+                        continue;
+                if (S_ISLNK(link->mode) && (link->data == link_root))
+                        continue;
+                return false;
+        }
+
+        /* The checks passed.  Increase the registration count on the links */
+        for (entry = table; entry->procname; entry++) {
+                const char *procname = entry->procname;
+                link = find_entry(&head, dir, procname, strlen(procname));
+                head->nreg++;
+        }
+        return true;
+}
+
+static int insert_links(struct ctl_table_header *head)
+{
+        struct ctl_table_set *root_set = &sysctl_table_root.default_set;
+        struct ctl_dir *core_parent = NULL;
+        struct ctl_table_header *links;
+        int err;
+
+        if (head->set == root_set)
+                return 0;
+
+        core_parent = xlate_dir(root_set, head->parent);
+        if (IS_ERR(core_parent))
+                return 0;
+
+        if (get_links(core_parent, head->ctl_table, head->root))
+                return 0;
+
+        core_parent->header.nreg++;
+        spin_unlock(&sysctl_lock);
+
+        links = new_links(core_parent, head->ctl_table, head->root);
+
+        spin_lock(&sysctl_lock);
+        err = -ENOMEM;
+        if (!links)
+                goto out;
+
+        err = 0;
+        if (get_links(core_parent, head->ctl_table, head->root)) {
+                kfree(links);
+                goto out;
+        }
+
+        err = insert_header(core_parent, links);
+        if (err)
+                kfree(links);
+out:
+        drop_sysctl_table(&core_parent->header);
+        return err;
+}
+
+/**
+ * __register_sysctl_table - register a leaf sysctl table
+ * @set: Sysctl tree to register on
+ * @path: The path to the directory the sysctl table is in.
+ * @table: the top-level table structure
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * The members of the &struct ctl_table structure are used as follows:
+ *
+ * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
+ *            enter a sysctl file
+ *
+ * data - a pointer to data for use by proc_handler
+ *
+ * maxlen - the maximum size in bytes of the data
+ *
+ * mode - the file permissions for the /proc/sys file
+ *
+ * child - must be %NULL.
+ *
+ * proc_handler - the text handler routine (described below)
+ *
+ * extra1, extra2 - extra pointers usable by the proc handler routines
+ *
+ * Leaf nodes in the sysctl tree will be represented by a single file
+ * under /proc; non-leaf nodes will be represented by directories.
+ *
+ * There must be a proc_handler routine for any terminal nodes.
+ * Several default handlers are available to cover common cases -
+ *
+ * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
+ * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
+ * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
+ *
+ * It is the handler's job to read the input buffer from user memory
+ * and process it. The handler should return 0 on success.
+ *
+ * This routine returns %NULL on a failure to register, and a pointer
+ * to the table header on success.
+ */
+struct ctl_table_header *__register_sysctl_table(
+        struct ctl_table_set *set,
+        const char *path, struct ctl_table *table)
+{
+        struct ctl_table_root *root = set->dir.header.root;
+        struct ctl_table_header *header;
+        const char *name, *nextname;
+        struct ctl_dir *dir;
+        struct ctl_table *entry;
+        struct ctl_node *node;
+        int nr_entries = 0;
+
+        for (entry = table; entry->procname; entry++)
+                nr_entries++;
+
+        header = kzalloc(sizeof(struct ctl_table_header) +
+                         sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
+        if (!header)
+                return NULL;
+
+        node = (struct ctl_node *)(header + 1);
+        init_header(header, root, set, node, table);
+        if (sysctl_check_table(path, table))
+                goto fail;
+
+        spin_lock(&sysctl_lock);
+        dir = &set->dir;
+        /* Reference moved down the diretory tree get_subdir */
+        dir->header.nreg++;
+        spin_unlock(&sysctl_lock);
+
+        /* Find the directory for the ctl_table */
+        for (name = path; name; name = nextname) {
+                int namelen;
+                nextname = strchr(name, '/');
+                if (nextname) {
+                        namelen = nextname - name;
+                        nextname++;
+                } else {
+                        namelen = strlen(name);
+                }
+                if (namelen == 0)
+                        continue;
+
+                dir = get_subdir(dir, name, namelen);
+                if (IS_ERR(dir))
+                        goto fail;
+        }
+
+        spin_lock(&sysctl_lock);
+        if (insert_header(dir, header))
+                goto fail_put_dir_locked;
+
+        drop_sysctl_table(&dir->header);
+        spin_unlock(&sysctl_lock);
+
+        return header;
+
+fail_put_dir_locked:
+        drop_sysctl_table(&dir->header);
+        spin_unlock(&sysctl_lock);
+fail:
+        kfree(header);
+        dump_stack();
+        return NULL;
+}
+
+/**
+ * register_sysctl - register a sysctl table
+ * @path: The path to the directory the sysctl table is in.
+ * @table: the table structure
+ *
+ * Register a sysctl table. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * See __register_sysctl_table for more details.
+ */
+struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
+{
+        return __register_sysctl_table(&sysctl_table_root.default_set,
+                                        path, table);
+}
+EXPORT_SYMBOL(register_sysctl);
+
+static char *append_path(const char *path, char *pos, const char *name)
+{
+        int namelen;
+        namelen = strlen(name);
+        if (((pos - path) + namelen + 2) >= PATH_MAX)
+                return NULL;
+        memcpy(pos, name, namelen);
+        pos[namelen] = '/';
+        pos[namelen + 1] = '\0';
+        pos += namelen + 1;
+        return pos;
+}
+
+static int count_subheaders(struct ctl_table *table)
+{
+        int has_files = 0;
+        int nr_subheaders = 0;
+        struct ctl_table *entry;
+
+        /* special case: no directory and empty directory */
+        if (!table || !table->procname)
+                return 1;
+
+        for (entry = table; entry->procname; entry++) {
+                if (entry->child)
+                        nr_subheaders += count_subheaders(entry->child);
+                else
+                        has_files = 1;
+        }
+        return nr_subheaders + has_files;
+}
+
+static int register_leaf_sysctl_tables(const char *path, char *pos,
+        struct ctl_table_header ***subheader, struct ctl_table_set *set,
+        struct ctl_table *table)
+{
+        struct ctl_table *ctl_table_arg = NULL;
+        struct ctl_table *entry, *files;
+        int nr_files = 0;
+        int nr_dirs = 0;
+        int err = -ENOMEM;
+
+        for (entry = table; entry->procname; entry++) {
+                if (entry->child)
+                        nr_dirs++;
+                else
+                        nr_files++;
+        }
+
+        files = table;
+        /* If there are mixed files and directories we need a new table */
+        if (nr_dirs && nr_files) {
+                struct ctl_table *new;
+                files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
+                                GFP_KERNEL);
+                if (!files)
+                        goto out;
+
+                ctl_table_arg = files;
+                for (new = files, entry = table; entry->procname; entry++) {
+                        if (entry->child)
+                                continue;
+                        *new = *entry;
+                        new++;
+                }
+        }
+
+        /* Register everything except a directory full of subdirectories */
+        if (nr_files || !nr_dirs) {
+                struct ctl_table_header *header;
+                header = __register_sysctl_table(set, path, files);
+                if (!header) {
+                        kfree(ctl_table_arg);
+                        goto out;
+                }
+
+                /* Remember if we need to free the file table */
+                header->ctl_table_arg = ctl_table_arg;
+                **subheader = header;
+                (*subheader)++;
+        }
+
+        /* Recurse into the subdirectories. */
+        for (entry = table; entry->procname; entry++) {
+                char *child_pos;
+
+                if (!entry->child)
+                        continue;
+
+                err = -ENAMETOOLONG;
+                child_pos = append_path(path, pos, entry->procname);
+                if (!child_pos)
+                        goto out;
+
+                err = register_leaf_sysctl_tables(path, child_pos, subheader,
+                                                  set, entry->child);
+                pos[0] = '\0';
+                if (err)
+                        goto out;
+        }
+        err = 0;
+out:
+        /* On failure our caller will unregister all registered subheaders */
+        return err;
+}
+
+/**
+ * __register_sysctl_paths - register a sysctl table hierarchy
+ * @set: Sysctl tree to register on
+ * @path: The path to the directory the sysctl table is in.
+ * @table: the top-level table structure
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * See __register_sysctl_table for more details.
+ */
+struct ctl_table_header *__register_sysctl_paths(
+        struct ctl_table_set *set,
+        const struct ctl_path *path, struct ctl_table *table)
+{
+        struct ctl_table *ctl_table_arg = table;
+        int nr_subheaders = count_subheaders(table);
+        struct ctl_table_header *header = NULL, **subheaders, **subheader;
+        const struct ctl_path *component;
+        char *new_path, *pos;
+
+        pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
+        if (!new_path)
+                return NULL;
+
+        pos[0] = '\0';
+        for (component = path; component->procname; component++) {
+                pos = append_path(new_path, pos, component->procname);
+                if (!pos)
+                        goto out;
+        }
+        while (table->procname && table->child && !table[1].procname) {
+                pos = append_path(new_path, pos, table->procname);
+                if (!pos)
+                        goto out;
+                table = table->child;
+        }
+        if (nr_subheaders == 1) {
+                header = __register_sysctl_table(set, new_path, table);
+                if (header)
+                        header->ctl_table_arg = ctl_table_arg;
+        } else {
+                header = kzalloc(sizeof(*header) +
+                                 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
+                if (!header)
+                        goto out;
+
+                subheaders = (struct ctl_table_header **) (header + 1);
+                subheader = subheaders;
+                header->ctl_table_arg = ctl_table_arg;
+
+                if (register_leaf_sysctl_tables(new_path, pos, &subheader,
+                                                set, table))
+                        goto err_register_leaves;
+        }
+
+out:
+        kfree(new_path);
+        return header;
+
+err_register_leaves:
+        while (subheader > subheaders) {
+                struct ctl_table_header *subh = *(--subheader);
+                struct ctl_table *table = subh->ctl_table_arg;
+                unregister_sysctl_table(subh);
+                kfree(table);
+        }
+        kfree(header);
+        header = NULL;
+        goto out;
+}
+
+/**
+ * register_sysctl_table_path - register a sysctl table hierarchy
+ * @path: The path to the directory the sysctl table is in.
+ * @table: the top-level table structure
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * See __register_sysctl_paths for more details.
+ */
+struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
+                                                struct ctl_table *table)
+{
+        return __register_sysctl_paths(&sysctl_table_root.default_set,
+                                        path, table);
+}
+EXPORT_SYMBOL(register_sysctl_paths);
+
+/**
+ * register_sysctl_table - register a sysctl table hierarchy
+ * @table: the top-level table structure
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * See register_sysctl_paths for more details.
+ */
+struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
+{
+        static const struct ctl_path null_path[] = { {} };
+
+        return register_sysctl_paths(null_path, table);
+}
+EXPORT_SYMBOL(register_sysctl_table);
+
+static void put_links(struct ctl_table_header *header)
+{
+        struct ctl_table_set *root_set = &sysctl_table_root.default_set;
+        struct ctl_table_root *root = header->root;
+        struct ctl_dir *parent = header->parent;
+        struct ctl_dir *core_parent;
+        struct ctl_table *entry;
+
+        if (header->set == root_set)
+                return;
+
+        core_parent = xlate_dir(root_set, parent);
+        if (IS_ERR(core_parent))
+                return;
+
+        for (entry = header->ctl_table; entry->procname; entry++) {
+                struct ctl_table_header *link_head;
+                struct ctl_table *link;
+                const char *name = entry->procname;
+
+                link = find_entry(&link_head, core_parent, name, strlen(name));
+                if (link &&
+                    ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
+                     (S_ISLNK(link->mode) && (link->data == root)))) {
+                        drop_sysctl_table(link_head);
+                }
+                else {
+                        printk(KERN_ERR "sysctl link missing during unregister: ");
+                        sysctl_print_dir(parent);
+                        printk(KERN_CONT "/%s\n", name);
+                }
+        }
+}
+
+static void drop_sysctl_table(struct ctl_table_header *header)
+{
+        struct ctl_dir *parent = header->parent;
+
+        if (--header->nreg)
+                return;
+
+        put_links(header);
+        start_unregistering(header);
+        if (!--header->count)
+                kfree_rcu(header, rcu);
+
+        if (parent)
+                drop_sysctl_table(&parent->header);
+}
+
+/**
+ * unregister_sysctl_table - unregister a sysctl table hierarchy
+ * @header: the header returned from register_sysctl_table
+ *
+ * Unregisters the sysctl table and all children. proc entries may not
+ * actually be removed until they are no longer used by anyone.
+ */
+void unregister_sysctl_table(struct ctl_table_header * header)
+{
+        int nr_subheaders;
+        might_sleep();
+
+        if (header == NULL)
+                return;
+
+        nr_subheaders = count_subheaders(header->ctl_table_arg);
+        if (unlikely(nr_subheaders > 1)) {
+                struct ctl_table_header **subheaders;
+                int i;
+
+                subheaders = (struct ctl_table_header **)(header + 1);
+                for (i = nr_subheaders -1; i >= 0; i--) {
+                        struct ctl_table_header *subh = subheaders[i];
+                        struct ctl_table *table = subh->ctl_table_arg;
+                        unregister_sysctl_table(subh);
+                        kfree(table);
+                }
+                kfree(header);
+                return;
+        }
+
+        spin_lock(&sysctl_lock);
+        drop_sysctl_table(header);
+        spin_unlock(&sysctl_lock);
+}
+EXPORT_SYMBOL(unregister_sysctl_table);
+
+void setup_sysctl_set(struct ctl_table_set *set,
+        struct ctl_table_root *root,
+        int (*is_seen)(struct ctl_table_set *))
+{
+        memset(set, 0, sizeof(*set));
+        set->is_seen = is_seen;
+        init_header(&set->dir.header, root, set, NULL, root_table);
+}
+
+void retire_sysctl_set(struct ctl_table_set *set)
+{
+        WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
+}
+
 int __init proc_sys_init(void)
 {
         struct proc_dir_entry *proc_sys_root;
@@ -480,5 +1601,6 @@ int __init proc_sys_init(void)
         proc_sys_root->proc_iops = &proc_sys_dir_operations;
         proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
         proc_sys_root->nlink = 0;
-        return 0;
+
+        return sysctl_init();
 }