[PATCH] sysctl: reimplement the sysctl proc support

With this change the sysctl inodes can be cached and nothing needs to be done
when removing a sysctl table.

For a cost of 2K code we will save about 4K of static tables (when we remove
de from ctl_table) and 70K in proc_dir_entries that we will not allocate, or
about half that on a 32bit arch.

The speed feels about the same, even though we can now cache the sysctl
dentries :(

We get the core advantage that we don't need to have a 1 to 1 mapping between
ctl table entries and proc files.  Making it possible to have /proc/sys vary
depending on the namespace you are in.  The currently merged namespaces don't
have an issue here but the network namespace under /proc/sys/net needs to have
different directories depending on which network adapters are visible.  By
simply being a cache different directories being visible depending on who you
are is trivial to implement.

[akpm@osdl.org: fix uninitialised var]
[akpm@osdl.org: fix ARM build]
[bunk@stusta.de: make things static]
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

10 files changed, 486 insertions, 199 deletions

diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index f6c776272572..a6b3a8f878f0 100644
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -8,7 +8,7 @@ proc-y			:= nommu.o task_nommu.o
 proc-$(CONFIG_MMU)      := mmu.o task_mmu.o
 
 proc-y       += inode.o root.o base.o generic.o array.o \
-                proc_tty.o proc_misc.o
+                proc_tty.o proc_misc.o proc_sysctl.o
 
 proc-$(CONFIG_PROC_KCORE)       += kcore.o
 proc-$(CONFIG_PROC_VMCORE)      += vmcore.o
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 0cdc00d9d97e..775fb21294d8 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -32,7 +32,7 @@ static loff_t proc_file_lseek(struct file *, loff_t, int);
 
 DEFINE_SPINLOCK(proc_subdir_lock);
 
-int proc_match(int len, const char *name, struct proc_dir_entry *de)
+static int proc_match(int len, const char *name, struct proc_dir_entry *de)
 {
         if (de->namelen != len)
                 return 0;
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index f6722be37dde..c372eb151a3a 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -161,6 +161,7 @@ struct inode *proc_get_inode(struct super_block *sb, unsigned int ino,
         if (!inode)
                 goto out_ino;
 
+        PROC_I(inode)->fd = 0;
         PROC_I(inode)->pde = de;
         if (de) {
                 if (de->mode) {
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 277dcd66ebe2..c932aa65e198 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -11,6 +11,8 @@
 
 #include <linux/proc_fs.h>
 
+extern int proc_sys_init(void);
+
 struct vmalloc_info {
         unsigned long   used;
         unsigned long   largest_chunk;
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
new file mode 100644
index 000000000000..bb16a1e78826
--- /dev/null
+++ b/fs/proc/proc_sysctl.c
@@ -0,0 +1,478 @@
+/*
+ * /proc/sys support
+ */
+
+#include <linux/sysctl.h>
+#include <linux/proc_fs.h>
+#include <linux/security.h>
+#include "internal.h"
+
+static struct dentry_operations proc_sys_dentry_operations;
+static const struct file_operations proc_sys_file_operations;
+static struct inode_operations proc_sys_inode_operations;
+
+static void proc_sys_refresh_inode(struct inode *inode, struct ctl_table *table)
+{
+        /* Refresh the cached information bits in the inode */
+        if (table) {
+                inode->i_uid = 0;
+                inode->i_gid = 0;
+                inode->i_mode = table->mode;
+                if (table->proc_handler) {
+                        inode->i_mode |= S_IFREG;
+                        inode->i_nlink = 1;
+                } else {
+                        inode->i_mode |= S_IFDIR;
+                        inode->i_nlink = 0;     /* It is too hard to figure out */
+                }
+        }
+}
+
+static struct inode *proc_sys_make_inode(struct inode *dir, struct ctl_table *table)
+{
+        struct inode *inode;
+        struct proc_inode *dir_ei, *ei;
+        int depth;
+
+        inode = new_inode(dir->i_sb);
+        if (!inode)
+                goto out;
+
+        /* A directory is always one deeper than it's parent */
+        dir_ei = PROC_I(dir);
+        depth = dir_ei->fd + 1;
+
+        ei = PROC_I(inode);
+        ei->fd = depth;
+        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+        inode->i_op = &proc_sys_inode_operations;
+        inode->i_fop = &proc_sys_file_operations;
+        proc_sys_refresh_inode(inode, table);
+out:
+        return inode;
+}
+
+static struct dentry *proc_sys_ancestor(struct dentry *dentry, int depth)
+{
+        for (;;) {
+                struct proc_inode *ei;
+
+                ei = PROC_I(dentry->d_inode);
+                if (ei->fd == depth)
+                        break; /* found */
+
+                dentry = dentry->d_parent;
+        }
+        return dentry;
+}
+
+static struct ctl_table *proc_sys_lookup_table_one(struct ctl_table *table,
+                                                        struct qstr *name)
+{
+        int len;
+        for ( ; table->ctl_name || table->procname; table++) {
+
+                if (!table->procname)
+                        continue;
+
+                len = strlen(table->procname);
+                if (len != name->len)
+                        continue;
+
+                if (memcmp(table->procname, name->name, len) != 0)
+                        continue;
+
+                /* I have a match */
+                return table;
+        }
+        return NULL;
+}
+
+static struct ctl_table *proc_sys_lookup_table(struct dentry *dentry,
+                                                struct ctl_table *table)
+{
+        struct dentry *ancestor;
+        struct proc_inode *ei;
+        int depth, i;
+
+        ei = PROC_I(dentry->d_inode);
+        depth = ei->fd;
+
+        if (depth == 0)
+                return table;
+
+        for (i = 1; table && (i <= depth); i++) {
+                ancestor = proc_sys_ancestor(dentry, i);
+                table = proc_sys_lookup_table_one(table, &ancestor->d_name);
+                if (table)
+                        table = table->child;
+        }
+        return table;
+
+}
+static struct ctl_table *proc_sys_lookup_entry(struct dentry *dparent,
+                                                struct qstr *name,
+                                                struct ctl_table *table)
+{
+        table = proc_sys_lookup_table(dparent, table);
+        if (table)
+                table = proc_sys_lookup_table_one(table, name);
+        return table;
+}
+
+static struct ctl_table *do_proc_sys_lookup(struct dentry *parent,
+                                                struct qstr *name,
+                                                struct ctl_table_header **ptr)
+{
+        struct ctl_table_header *head;
+        struct ctl_table *table = NULL;
+
+        for (head = sysctl_head_next(NULL); head;
+                        head = sysctl_head_next(head)) {
+                table = proc_sys_lookup_entry(parent, name, head->ctl_table);
+                if (table)
+                        break;
+        }
+        *ptr = head;
+        return table;
+}
+
+static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
+                                        struct nameidata *nd)
+{
+        struct ctl_table_header *head;
+        struct inode *inode;
+        struct dentry *err;
+        struct ctl_table *table;
+
+        err = ERR_PTR(-ENOENT);
+        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
+        if (!table)
+                goto out;
+
+        err = ERR_PTR(-ENOMEM);
+        inode = proc_sys_make_inode(dir, table);
+        if (!inode)
+                goto out;
+
+        err = NULL;
+        dentry->d_op = &proc_sys_dentry_operations;
+        d_add(dentry, inode);
+
+out:
+        sysctl_head_finish(head);
+        return err;
+}
+
+static ssize_t proc_sys_read(struct file *filp, char __user *buf,
+                                size_t count, loff_t *ppos)
+{
+        struct dentry *dentry = filp->f_dentry;
+        struct ctl_table_header *head;
+        struct ctl_table *table;
+        ssize_t error, res;
+
+        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
+        /* Has the sysctl entry disappeared on us? */
+        error = -ENOENT;
+        if (!table)
+                goto out;
+
+        /* Has the sysctl entry been replaced by a directory? */
+        error = -EISDIR;
+        if (!table->proc_handler)
+                goto out;
+
+        /*
+         * At this point we know that the sysctl was not unregistered
+         * and won't be until we finish.
+         */
+        error = -EPERM;
+        if (sysctl_perm(table, MAY_READ))
+                goto out;
+
+        /* careful: calling conventions are nasty here */
+        res = count;
+        error = table->proc_handler(table, 0, filp, buf, &res, ppos);
+        if (!error)
+                error = res;
+out:
+        sysctl_head_finish(head);
+
+        return error;
+}
+
+static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
+                                size_t count, loff_t *ppos)
+{
+        struct dentry *dentry = filp->f_dentry;
+        struct ctl_table_header *head;
+        struct ctl_table *table;
+        ssize_t error, res;
+
+        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
+        /* Has the sysctl entry disappeared on us? */
+        error = -ENOENT;
+        if (!table)
+                goto out;
+
+        /* Has the sysctl entry been replaced by a directory? */
+        error = -EISDIR;
+        if (!table->proc_handler)
+                goto out;
+
+        /*
+         * At this point we know that the sysctl was not unregistered
+         * and won't be until we finish.
+         */
+        error = -EPERM;
+        if (sysctl_perm(table, MAY_WRITE))
+                goto out;
+
+        /* careful: calling conventions are nasty here */
+        res = count;
+        error = table->proc_handler(table, 1, filp, (char __user *)buf,
+                                    &res, ppos);
+        if (!error)
+                error = res;
+out:
+        sysctl_head_finish(head);
+
+        return error;
+}
+
+
+static int proc_sys_fill_cache(struct file *filp, void *dirent,
+                                filldir_t filldir, struct ctl_table *table)
+{
+        struct ctl_table_header *head;
+        struct ctl_table *child_table = NULL;
+        struct dentry *child, *dir = filp->f_path.dentry;
+        struct inode *inode;
+        struct qstr qname;
+        ino_t ino = 0;
+        unsigned type = DT_UNKNOWN;
+        int ret;
+
+        qname.name = table->procname;
+        qname.len  = strlen(table->procname);
+        qname.hash = full_name_hash(qname.name, qname.len);
+
+        /* Suppress duplicates.
+         * Only fill a directory entry if it is the value that
+         * an ordinary lookup of that name returns.  Hide all
+         * others.
+         *
+         * If we ever cache this translation in the dcache
+         * I should do a dcache lookup first.  But for now
+         * it is just simpler not to.
+         */
+        ret = 0;
+        child_table = do_proc_sys_lookup(dir, &qname, &head);
+        sysctl_head_finish(head);
+        if (child_table != table)
+                return 0;
+
+        child = d_lookup(dir, &qname);
+        if (!child) {
+                struct dentry *new;
+                new = d_alloc(dir, &qname);
+                if (new) {
+                        inode = proc_sys_make_inode(dir->d_inode, table);
+                        if (!inode)
+                                child = ERR_PTR(-ENOMEM);
+                        else {
+                                new->d_op = &proc_sys_dentry_operations;
+                                d_add(new, inode);
+                        }
+                        if (child)
+                                dput(new);
+                        else
+                                child = new;
+                }
+        }
+        if (!child || IS_ERR(child) || !child->d_inode)
+                goto end_instantiate;
+        inode = child->d_inode;
+        if (inode) {
+                ino  = inode->i_ino;
+                type = inode->i_mode >> 12;
+        }
+        dput(child);
+end_instantiate:
+        if (!ino)
+                ino= find_inode_number(dir, &qname);
+        if (!ino)
+                ino = 1;
+        return filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
+}
+
+static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+        struct dentry *dentry = filp->f_dentry;
+        struct inode *inode = dentry->d_inode;
+        struct ctl_table_header *head = NULL;
+        struct ctl_table *table;
+        unsigned long pos;
+        int ret;
+
+        ret = -ENOTDIR;
+        if (!S_ISDIR(inode->i_mode))
+                goto out;
+
+        ret = 0;
+        /* Avoid a switch here: arm builds fail with missing __cmpdi2 */
+        if (filp->f_pos == 0) {
+                if (filldir(dirent, ".", 1, filp->f_pos,
+                                inode->i_ino, DT_DIR) < 0)
+                        goto out;
+                filp->f_pos++;
+        }
+        if (filp->f_pos == 1) {
+                if (filldir(dirent, "..", 2, filp->f_pos,
+                                parent_ino(dentry), DT_DIR) < 0)
+                        goto out;
+                filp->f_pos++;
+        }
+        pos = 2;
+
+        /* - Find each instance of the directory
+         * - Read all entries in each instance
+         * - Before returning an entry to user space lookup the entry
+         *   by name and if I find a different entry don't return
+         *   this one because it means it is a buried dup.
+         * For sysctl this should only happen for directory entries.
+         */
+        for (head = sysctl_head_next(NULL); head; head = sysctl_head_next(head)) {
+                table = proc_sys_lookup_table(dentry, head->ctl_table);
+
+                if (!table)
+                        continue;
+
+                for (; table->ctl_name || table->procname; table++, pos++) {
+                        /* Can't do anything without a proc name */
+                        if (!table->procname)
+                                continue;
+
+                        if (pos < filp->f_pos)
+                                continue;
+
+                        if (proc_sys_fill_cache(filp, dirent, filldir, table) < 0)
+                                goto out;
+                        filp->f_pos = pos + 1;
+                }
+        }
+        ret = 1;
+out:
+        sysctl_head_finish(head);
+        return ret;
+}
+
+static int proc_sys_permission(struct inode *inode, int mask, struct nameidata *nd)
+{
+        /*
+         * sysctl entries that are not writeable,
+         * are _NOT_ writeable, capabilities or not.
+         */
+        struct ctl_table_header *head;
+        struct ctl_table *table;
+        struct dentry *dentry;
+        int mode;
+        int depth;
+        int error;
+
+        head = NULL;
+        depth = PROC_I(inode)->fd;
+
+        /* First check the cached permissions, in case we don't have
+         * enough information to lookup the sysctl table entry.
+         */
+        error = -EACCES;
+        mode = inode->i_mode;
+
+        if (current->euid == 0)
+                mode >>= 6;
+        else if (in_group_p(0))
+                mode >>= 3;
+
+        if ((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)
+                error = 0;
+
+        /* If we can't get a sysctl table entry the permission
+         * checks on the cached mode will have to be enough.
+         */
+        if (!nd || !depth)
+                goto out;
+
+        dentry = nd->dentry;
+        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
+
+        /* If the entry does not exist deny permission */
+        error = -EACCES;
+        if (!table)
+                goto out;
+
+        /* Use the permissions on the sysctl table entry */
+        error = sysctl_perm(table, mask);
+out:
+        sysctl_head_finish(head);
+        return error;
+}
+
+static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
+{
+        struct inode *inode = dentry->d_inode;
+        int error;
+
+        if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
+                return -EPERM;
+
+        error = inode_change_ok(inode, attr);
+        if (!error) {
+                error = security_inode_setattr(dentry, attr);
+                if (!error)
+                        error = inode_setattr(inode, attr);
+        }
+
+        return error;
+}
+
+/* I'm lazy and don't distinguish between files and directories,
+ * until access time.
+ */
+static const struct file_operations proc_sys_file_operations = {
+        .read           = proc_sys_read,
+        .write          = proc_sys_write,
+        .readdir        = proc_sys_readdir,
+};
+
+static struct inode_operations proc_sys_inode_operations = {
+        .lookup         = proc_sys_lookup,
+        .permission     = proc_sys_permission,
+        .setattr        = proc_sys_setattr,
+};
+
+static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+        struct ctl_table_header *head;
+        struct ctl_table *table;
+        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
+        proc_sys_refresh_inode(dentry->d_inode, table);
+        sysctl_head_finish(head);
+        return !!table;
+}
+
+static struct dentry_operations proc_sys_dentry_operations = {
+        .d_revalidate   = proc_sys_revalidate,
+};
+
+static struct proc_dir_entry *proc_sys_root;
+
+int proc_sys_init(void)
+{
+        proc_sys_root = proc_mkdir("sys", NULL);
+        proc_sys_root->proc_iops = &proc_sys_inode_operations;
+        proc_sys_root->proc_fops = &proc_sys_file_operations;
+        proc_sys_root->nlink = 0;
+        return 0;
+}
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 6ae222b509ce..5834a744c2a9 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -23,10 +23,6 @@
 
 struct proc_dir_entry *proc_net, *proc_net_stat, *proc_bus, *proc_root_fs, *proc_root_driver;
 
-#ifdef CONFIG_SYSCTL
-struct proc_dir_entry *proc_sys_root;
-#endif
-
 static int proc_get_sb(struct file_system_type *fs_type,
         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
@@ -71,9 +67,6 @@ void __init proc_root_init(void)
 #ifdef CONFIG_SYSVIPC
         proc_mkdir("sysvipc", NULL);
 #endif
-#ifdef CONFIG_SYSCTL
-        proc_sys_root = proc_mkdir("sys", NULL);
-#endif
         proc_root_fs = proc_mkdir("fs", NULL);
         proc_root_driver = proc_mkdir("driver", NULL);
         proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
@@ -86,6 +79,9 @@ void __init proc_root_init(void)
         proc_device_tree_init();
 #endif
         proc_bus = proc_mkdir("bus", NULL);
+#ifdef CONFIG_SYSCTL
+        proc_sys_init();
+#endif
 }
 
 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 2e132473cbe5..be4652a0545a 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -113,8 +113,6 @@ extern struct vfsmount *proc_mnt;
 extern int proc_fill_super(struct super_block *,void *,int);
 extern struct inode *proc_get_inode(struct super_block *, unsigned int, struct proc_dir_entry *);
 
-extern int proc_match(int, const char *,struct proc_dir_entry *);
-
 /*
  * These are generic /proc routines that use the internal
  * "struct proc_dir_entry" tree to traverse the filesystem.
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 9698ac30f553..89150494bd10 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -930,8 +930,6 @@ extern struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev);
 extern void sysctl_head_finish(struct ctl_table_header *prev);
 extern int sysctl_perm(struct ctl_table *table, int op);
 
-extern void sysctl_init(void);
-
 typedef struct ctl_table ctl_table;
 
 typedef int ctl_handler (ctl_table *table, int __user *name, int nlen,
diff --git a/init/main.c b/init/main.c
index a20a5138211f..649ab5443d43 100644
--- a/init/main.c
+++ b/init/main.c
@@ -86,7 +86,6 @@ extern void init_IRQ(void);
 extern void fork_init(unsigned long);
 extern void mca_init(void);
 extern void sbus_init(void);
-extern void sysctl_init(void);
 extern void signals_init(void);
 extern void pidhash_init(void);
 extern void pidmap_init(void);
@@ -702,9 +701,6 @@ static void __init do_basic_setup(void)
         usermodehelper_init();
         driver_init();
 
-#ifdef CONFIG_SYSCTL
-        sysctl_init();
-#endif
 #ifdef CONFIG_PROC_FS
         init_irq_proc();
 #endif
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6bbac5ce75ed..b3ee791ad663 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -159,26 +159,6 @@ int sysctl_legacy_va_layout;
 #endif
 
 
-/* /proc declarations: */
-
-#ifdef CONFIG_PROC_SYSCTL
-
-static ssize_t proc_readsys(struct file *, char __user *, size_t, loff_t *);
-static ssize_t proc_writesys(struct file *, const char __user *, size_t, loff_t *);
-static int proc_opensys(struct inode *, struct file *);
-
-const struct file_operations proc_sys_file_operations = {
-        .open           = proc_opensys,
-        .read           = proc_readsys,
-        .write          = proc_writesys,
-};
-
-extern struct proc_dir_entry *proc_sys_root;
-
-static void register_proc_table(ctl_table *, struct proc_dir_entry *, void *);
-static void unregister_proc_table(ctl_table *, struct proc_dir_entry *);
-#endif
-
 /* The default sysctl tables: */
 
 static ctl_table root_table[] = {
@@ -1106,13 +1086,6 @@ struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev)
         return NULL;
 }
 
-void __init sysctl_init(void)
-{
-#ifdef CONFIG_PROC_SYSCTL
-        register_proc_table(root_table, proc_sys_root, &root_table_header);
-#endif
-}
-
 #ifdef CONFIG_SYSCTL_SYSCALL
 int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *oldlenp,
                void __user *newval, size_t newlen)
@@ -1348,9 +1321,6 @@ struct ctl_table_header *register_sysctl_table(ctl_table * table)
         spin_lock(&sysctl_lock);
         list_add_tail(&tmp->ctl_entry, &root_table_header.ctl_entry);
         spin_unlock(&sysctl_lock);
-#ifdef CONFIG_PROC_SYSCTL
-        register_proc_table(table, proc_sys_root, tmp);
-#endif
         return tmp;
 }
 
@@ -1366,9 +1336,6 @@ void unregister_sysctl_table(struct ctl_table_header * header)
         might_sleep();
         spin_lock(&sysctl_lock);
         start_unregistering(header);
-#ifdef CONFIG_PROC_SYSCTL
-        unregister_proc_table(header->ctl_table, proc_sys_root);
-#endif
         spin_unlock(&sysctl_lock);
         kfree(header);
 }
@@ -1392,155 +1359,6 @@ void unregister_sysctl_table(struct ctl_table_header * table)
 
 #ifdef CONFIG_PROC_SYSCTL
 
-/* Scan the sysctl entries in table and add them all into /proc */
-static void register_proc_table(ctl_table * table, struct proc_dir_entry *root, void *set)
-{
-        struct proc_dir_entry *de;
-        int len;
-        mode_t mode;
-        
-        for (; table->ctl_name || table->procname; table++) {
-                /* Can't do anything without a proc name. */
-                if (!table->procname)
-                        continue;
-                /* Maybe we can't do anything with it... */
-                if (!table->proc_handler && !table->child) {
-                        printk(KERN_WARNING "SYSCTL: Can't register %s\n",
-                                table->procname);
-                        continue;
-                }
-
-                len = strlen(table->procname);
-                mode = table->mode;
-
-                de = NULL;
-                if (table->proc_handler)
-                        mode |= S_IFREG;
-                else {
-                        mode |= S_IFDIR;
-                        for (de = root->subdir; de; de = de->next) {
-                                if (proc_match(len, table->procname, de))
-                                        break;
-                        }
-                        /* If the subdir exists already, de is non-NULL */
-                }
-
-                if (!de) {
-                        de = create_proc_entry(table->procname, mode, root);
-                        if (!de)
-                                continue;
-                        de->set = set;
-                        de->data = (void *) table;
-                        if (table->proc_handler)
-                                de->proc_fops = &proc_sys_file_operations;
-                }
-                table->de = de;
-                if (de->mode & S_IFDIR)
-                        register_proc_table(table->child, de, set);
-        }
-}
-
-/*
- * Unregister a /proc sysctl table and any subdirectories.
- */
-static void unregister_proc_table(ctl_table * table, struct proc_dir_entry *root)
-{
-        struct proc_dir_entry *de;
-        for (; table->ctl_name || table->procname; table++) {
-                if (!(de = table->de))
-                        continue;
-                if (de->mode & S_IFDIR) {
-                        if (!table->child) {
-                                printk (KERN_ALERT "Help - malformed sysctl tree on free\n");
-                                continue;
-                        }
-                        unregister_proc_table(table->child, de);
-
-                        /* Don't unregister directories which still have entries.. */
-                        if (de->subdir)
-                                continue;
-                }
-
-                /*
-                 * In any case, mark the entry as goner; we'll keep it
-                 * around if it's busy, but we'll know to do nothing with
-                 * its fields.  We are under sysctl_lock here.
-                 */
-                de->data = NULL;
-
-                /* Don't unregister proc entries that are still being used.. */
-                if (atomic_read(&de->count))
-                        continue;
-
-                table->de = NULL;
-                remove_proc_entry(table->procname, root);
-        }
-}
-
-static ssize_t do_rw_proc(int write, struct file * file, char __user * buf,
-                          size_t count, loff_t *ppos)
-{
-        int op;
-        struct proc_dir_entry *de = PDE(file->f_path.dentry->d_inode);
-        struct ctl_table *table;
-        size_t res;
-        ssize_t error = -ENOTDIR;
-        
-        spin_lock(&sysctl_lock);
-        if (de && de->data && use_table(de->set)) {
-                /*
-                 * at that point we know that sysctl was not unregistered
-                 * and won't be until we finish
-                 */
-                spin_unlock(&sysctl_lock);
-                table = (struct ctl_table *) de->data;
-                if (!table || !table->proc_handler)
-                        goto out;
-                error = -EPERM;
-                op = (write ? 002 : 004);
-                if (sysctl_perm(table, op))
-                        goto out;
-                
-                /* careful: calling conventions are nasty here */
-                res = count;
-                error = (*table->proc_handler)(table, write, file,
-                                                buf, &res, ppos);
-                if (!error)
-                        error = res;
-        out:
-                spin_lock(&sysctl_lock);
-                unuse_table(de->set);
-        }
-        spin_unlock(&sysctl_lock);
-        return error;
-}
-
-static int proc_opensys(struct inode *inode, struct file *file)
-{
-        if (file->f_mode & FMODE_WRITE) {
-                /*
-                 * sysctl entries that are not writable,
-                 * are _NOT_ writable, capabilities or not.
-                 */
-                if (!(inode->i_mode & S_IWUSR))
-                        return -EPERM;
-        }
-
-        return 0;
-}
-
-static ssize_t proc_readsys(struct file * file, char __user * buf,
-                            size_t count, loff_t *ppos)
-{
-        return do_rw_proc(0, file, buf, count, ppos);
-}
-
-static ssize_t proc_writesys(struct file * file, const char __user * buf,
-                             size_t count, loff_t *ppos)
-{
-        return do_rw_proc(1, file, (char __user *) buf, count, ppos);
-}
-
 static int _proc_do_string(void* data, int maxlen, int write,
                            struct file *filp, void __user *buffer,
                            size_t *lenp, loff_t *ppos)