diff options
Diffstat (limited to 'fs/devpts/inode.c')
| -rw-r--r-- | fs/devpts/inode.c | 43 |
1 files changed, 42 insertions, 1 deletions
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index f120e120787..285b64a8b06 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -17,6 +17,8 @@ #include <linux/namei.h> #include <linux/mount.h> #include <linux/tty.h> +#include <linux/mutex.h> +#include <linux/idr.h> #include <linux/devpts_fs.h> #include <linux/parser.h> #include <linux/fsnotify.h> @@ -26,6 +28,10 @@ #define DEVPTS_DEFAULT_MODE 0600 +extern int pty_limit; /* Config limit on Unix98 ptys */ +static DEFINE_IDR(allocated_ptys); +static DEFINE_MUTEX(allocated_ptys_lock); + static struct vfsmount *devpts_mnt; static struct dentry *devpts_root; @@ -171,9 +177,44 @@ static struct dentry *get_node(int num) return lookup_one_len(s, root, sprintf(s, "%d", num)); } +int devpts_new_index(void) +{ + int index; + int idr_ret; + +retry: + if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) { + return -ENOMEM; + } + + mutex_lock(&allocated_ptys_lock); + idr_ret = idr_get_new(&allocated_ptys, NULL, &index); + if (idr_ret < 0) { + mutex_unlock(&allocated_ptys_lock); + if (idr_ret == -EAGAIN) + goto retry; + return -EIO; + } + + if (index >= pty_limit) { + idr_remove(&allocated_ptys, index); + mutex_unlock(&allocated_ptys_lock); + return -EIO; + } + mutex_unlock(&allocated_ptys_lock); + return index; +} + +void devpts_kill_index(int idx) +{ + mutex_lock(&allocated_ptys_lock); + idr_remove(&allocated_ptys, idx); + mutex_unlock(&allocated_ptys_lock); +} + int devpts_pty_new(struct tty_struct *tty) { - int number = tty->index; + int number = tty->index; /* tty layer puts index from devpts_new_index() in here */ struct tty_driver *driver = tty->driver; dev_t device = MKDEV(driver->major, driver->minor_start+number); struct dentry *dentry; |