[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>

1 files changed, 0 insertions, 182 deletions

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)