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/fs/devpts/inode.c b/fs/devpts/inode.c
index c4e2a58..c2c7317 100644
--- 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 @@
mutex_unlock(&allocated_ptys_lock);
return -EIO;
}
+ pty_count++;
mutex_unlock(&allocated_ptys_lock);
return index;
}
@@ -462,6 +508,7 @@
mutex_lock(&allocated_ptys_lock);
ida_remove(&fsi->allocated_ptys, idx);
+ pty_count--;
mutex_unlock(&allocated_ptys_lock);
}
@@ -558,11 +605,15 @@
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;