diff options
Diffstat (limited to 'drivers/char/pty.c')
| -rw-r--r-- | drivers/char/pty.c | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/drivers/char/pty.c b/drivers/char/pty.c index ec09c1cd4fe..328e8ac1230 100644 --- a/drivers/char/pty.c +++ b/drivers/char/pty.c @@ -23,6 +23,7 @@ #include <linux/mm.h> #include <linux/init.h> #include <linux/sysctl.h> +#include <linux/device.h> #include <asm/uaccess.h> #include <asm/system.h> @@ -332,6 +333,8 @@ int pty_limit = NR_UNIX98_PTY_DEFAULT; static int pty_limit_min = 0; static int pty_limit_max = NR_UNIX98_PTY_MAX; +static struct cdev ptmx_cdev; + static struct ctl_table pty_table[] = { { .ctl_name = PTY_MAX, @@ -408,6 +411,70 @@ static const struct tty_operations ptm_unix98_ops = { .shutdown = pty_shutdown }; + +/** + * ptmx_open - open a unix 98 pty master + * @inode: inode of device file + * @filp: file pointer to tty + * + * Allocate a unix98 pty master device from the ptmx driver. + * + * Locking: tty_mutex protects the init_dev work. tty->count should + * protect the rest. + * allocated_ptys_lock handles the list of free pty numbers + */ + +static int __ptmx_open(struct inode *inode, struct file *filp) +{ + struct tty_struct *tty; + int retval; + int index; + + nonseekable_open(inode, filp); + + /* find a device that is not in use. */ + index = devpts_new_index(); + if (index < 0) + return index; + + mutex_lock(&tty_mutex); + retval = tty_init_dev(ptm_driver, index, &tty, 1); + mutex_unlock(&tty_mutex); + + if (retval) + goto out; + + set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ + filp->private_data = tty; + file_move(filp, &tty->tty_files); + + retval = devpts_pty_new(tty->link); + if (retval) + goto out1; + + retval = ptm_driver->ops->open(tty, filp); + if (!retval) + return 0; +out1: + tty_release_dev(filp); + return retval; +out: + devpts_kill_index(index); + return retval; +} + +static int ptmx_open(struct inode *inode, struct file *filp) +{ + int ret; + + lock_kernel(); + ret = __ptmx_open(inode, filp); + unlock_kernel(); + return ret; +} + +static struct file_operations ptmx_fops; + static void __init unix98_pty_init(void) { ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX); @@ -459,7 +526,18 @@ static void __init unix98_pty_init(void) pty_table[1].data = &ptm_driver->refcount; register_sysctl_table(pty_root_table); + + /* Now create the /dev/ptmx special device */ + tty_default_fops(&ptmx_fops); + ptmx_fops.open = ptmx_open; + + cdev_init(&ptmx_cdev, &ptmx_fops); + if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) || + register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0) + panic("Couldn't register /dev/ptmx driver\n"); + device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx"); } + #else static inline void unix98_pty_init(void) { } #endif |