tty: move pty count limiting into devpts

Let's move this stuff to the better place, where we can account pty right in
tty-indexes managing code.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 03147fa..d505837 100644 (file)
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -21,7 +21,6 @@
 #include <linux/major.h>
 #include <linux/mm.h>
 #include <linux/init.h>
-#include <linux/sysctl.h>
 #include <linux/device.h>
 #include <linux/uaccess.h>
 #include <linux/bitops.h>
@@ -439,55 +438,9 @@ static inline void legacy_pty_init(void) { }
 
 /* Unix98 devices */
 #ifdef CONFIG_UNIX98_PTYS
-/*
- * sysctl support for setting limits on the number of Unix98 ptys allocated.
- * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
- */
-int pty_limit = NR_UNIX98_PTY_DEFAULT;
-static int pty_limit_min;
-static int pty_limit_max = NR_UNIX98_PTY_MAX;
-static int pty_count;
 
 static struct cdev ptmx_cdev;
 
-static struct ctl_table pty_table[] = {
-       {
-               .procname       = "max",
-               .maxlen         = sizeof(int),
-               .mode           = 0644,
-               .data           = &pty_limit,
-               .proc_handler   = proc_dointvec_minmax,
-               .extra1         = &pty_limit_min,
-               .extra2         = &pty_limit_max,
-       }, {
-               .procname       = "nr",
-               .maxlen         = sizeof(int),
-               .mode           = 0444,
-               .data           = &pty_count,
-               .proc_handler   = proc_dointvec,
-       }, 
-       {}
-};
-
-static struct ctl_table pty_kern_table[] = {
-       {
-               .procname       = "pty",
-               .mode           = 0555,
-               .child          = pty_table,
-       },
-       {}
-};
-
-static struct ctl_table pty_root_table[] = {
-       {
-               .procname       = "kernel",
-               .mode           = 0555,
-               .child          = pty_kern_table,
-       },
-       {}
-};
-
-
 static int pty_unix98_ioctl(struct tty_struct *tty,
                            unsigned int cmd, unsigned long arg)
 {
@@ -587,7 +540,6 @@ static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
         */
        tty_driver_kref_get(driver);
        tty->count++;
-       pty_count++;
        return 0;
 err_free_mem:
        deinitialize_tty_struct(o_tty);
@@ -601,7 +553,6 @@ err_free_tty:
 
 static void ptm_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 {
-       pty_count--;
 }
 
 static void pts_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
@@ -760,8 +711,6 @@ static void __init unix98_pty_init(void)
        if (tty_register_driver(pts_driver))
                panic("Couldn't register Unix98 pts driver");
 
-       register_sysctl_table(pty_root_table);
-
        /* Now create the /dev/ptmx special device */
        tty_default_fops(&ptmx_fops);
        ptmx_fops.open = ptmx_open;

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index c4e2a58..c2c7317 100644 (file)
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -36,7 +36,52 @@
 #define DEVPTS_DEFAULT_PTMX_MODE 0000
 #define PTMX_MINOR     2
 
-extern int pty_limit;                  /* Config limit on Unix98 ptys */
+/*
+ * sysctl support for setting limits on the number of Unix98 ptys allocated.
+ * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
+ */
+static int pty_limit = NR_UNIX98_PTY_DEFAULT;
+static int pty_limit_min;
+static int pty_limit_max = NR_UNIX98_PTY_MAX;
+static int pty_count;
+
+static struct ctl_table pty_table[] = {
+       {
+               .procname       = "max",
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .data           = &pty_limit,
+               .proc_handler   = proc_dointvec_minmax,
+               .extra1         = &pty_limit_min,
+               .extra2         = &pty_limit_max,
+       }, {
+               .procname       = "nr",
+               .maxlen         = sizeof(int),
+               .mode           = 0444,
+               .data           = &pty_count,
+               .proc_handler   = proc_dointvec,
+       },
+       {}
+};
+
+static struct ctl_table pty_kern_table[] = {
+       {
+               .procname       = "pty",
+               .mode           = 0555,
+               .child          = pty_table,
+       },
+       {}
+};
+
+static struct ctl_table pty_root_table[] = {
+       {
+               .procname       = "kernel",
+               .mode           = 0555,
+               .child          = pty_kern_table,
+       },
+       {}
+};
+
 static DEFINE_MUTEX(allocated_ptys_lock);
 
 static struct vfsmount *devpts_mnt;
@@ -451,6 +496,7 @@ retry:
                mutex_unlock(&allocated_ptys_lock);
                return -EIO;
        }
+       pty_count++;
        mutex_unlock(&allocated_ptys_lock);
        return index;
 }
@@ -462,6 +508,7 @@ void devpts_kill_index(struct inode *ptmx_inode, int idx)
 
        mutex_lock(&allocated_ptys_lock);
        ida_remove(&fsi->allocated_ptys, idx);
+       pty_count--;
        mutex_unlock(&allocated_ptys_lock);
 }
 
@@ -558,11 +605,15 @@ void devpts_pty_kill(struct tty_struct *tty)
 static int __init init_devpts_fs(void)
 {
        int err = register_filesystem(&devpts_fs_type);
+       struct ctl_table_header *table;
+
        if (!err) {
+               table = register_sysctl_table(pty_root_table);
                devpts_mnt = kern_mount(&devpts_fs_type);
                if (IS_ERR(devpts_mnt)) {
                        err = PTR_ERR(devpts_mnt);
                        unregister_filesystem(&devpts_fs_type);
+                       unregister_sysctl_table(table);
                }
        }
        return err;