v4.19.13 snapshot.
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
new file mode 100644
index 0000000..d6f42b5
--- /dev/null
+++ b/drivers/tty/tty_io.c
@@ -0,0 +1,3355 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+/*
+ * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
+ * or rs-channels. It also implements echoing, cooked mode etc.
+ *
+ * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
+ *
+ * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
+ * tty_struct and tty_queue structures. Previously there was an array
+ * of 256 tty_struct's which was statically allocated, and the
+ * tty_queue structures were allocated at boot time. Both are now
+ * dynamically allocated only when the tty is open.
+ *
+ * Also restructured routines so that there is more of a separation
+ * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
+ * the low-level tty routines (serial.c, pty.c, console.c). This
+ * makes for cleaner and more compact code. -TYT, 9/17/92
+ *
+ * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
+ * which can be dynamically activated and de-activated by the line
+ * discipline handling modules (like SLIP).
+ *
+ * NOTE: pay no attention to the line discipline code (yet); its
+ * interface is still subject to change in this version...
+ * -- TYT, 1/31/92
+ *
+ * Added functionality to the OPOST tty handling. No delays, but all
+ * other bits should be there.
+ * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
+ *
+ * Rewrote canonical mode and added more termios flags.
+ * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
+ *
+ * Reorganized FASYNC support so mouse code can share it.
+ * -- ctm@ardi.com, 9Sep95
+ *
+ * New TIOCLINUX variants added.
+ * -- mj@k332.feld.cvut.cz, 19-Nov-95
+ *
+ * Restrict vt switching via ioctl()
+ * -- grif@cs.ucr.edu, 5-Dec-95
+ *
+ * Move console and virtual terminal code to more appropriate files,
+ * implement CONFIG_VT and generalize console device interface.
+ * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
+ *
+ * Rewrote tty_init_dev and tty_release_dev to eliminate races.
+ * -- Bill Hawes <whawes@star.net>, June 97
+ *
+ * Added devfs support.
+ * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
+ *
+ * Added support for a Unix98-style ptmx device.
+ * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
+ *
+ * Reduced memory usage for older ARM systems
+ * -- Russell King <rmk@arm.linux.org.uk>
+ *
+ * Move do_SAK() into process context. Less stack use in devfs functions.
+ * alloc_tty_struct() always uses kmalloc()
+ * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
+ */
+
+#include <linux/types.h>
+#include <linux/major.h>
+#include <linux/errno.h>
+#include <linux/signal.h>
+#include <linux/fcntl.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/interrupt.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+#include <linux/devpts_fs.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/console.h>
+#include <linux/timer.h>
+#include <linux/ctype.h>
+#include <linux/kd.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/proc_fs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/wait.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/seq_file.h>
+#include <linux/serial.h>
+#include <linux/ratelimit.h>
+
+#include <linux/uaccess.h>
+
+#include <linux/kbd_kern.h>
+#include <linux/vt_kern.h>
+#include <linux/selection.h>
+
+#include <linux/kmod.h>
+#include <linux/nsproxy.h>
+
+#undef TTY_DEBUG_HANGUP
+#ifdef TTY_DEBUG_HANGUP
+# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
+#else
+# define tty_debug_hangup(tty, f, args...) do { } while (0)
+#endif
+
+#define TTY_PARANOIA_CHECK 1
+#define CHECK_TTY_COUNT 1
+
+struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
+ .c_iflag = ICRNL | IXON,
+ .c_oflag = OPOST | ONLCR,
+ .c_cflag = B38400 | CS8 | CREAD | HUPCL,
+ .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
+ ECHOCTL | ECHOKE | IEXTEN,
+ .c_cc = INIT_C_CC,
+ .c_ispeed = 38400,
+ .c_ospeed = 38400,
+ /* .c_line = N_TTY, */
+};
+
+EXPORT_SYMBOL(tty_std_termios);
+
+/* This list gets poked at by procfs and various bits of boot up code. This
+ could do with some rationalisation such as pulling the tty proc function
+ into this file */
+
+LIST_HEAD(tty_drivers); /* linked list of tty drivers */
+
+/* Mutex to protect creating and releasing a tty */
+DEFINE_MUTEX(tty_mutex);
+
+static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
+static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
+ssize_t redirected_tty_write(struct file *, const char __user *,
+ size_t, loff_t *);
+static __poll_t tty_poll(struct file *, poll_table *);
+static int tty_open(struct inode *, struct file *);
+long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
+#ifdef CONFIG_COMPAT
+static long tty_compat_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg);
+#else
+#define tty_compat_ioctl NULL
+#endif
+static int __tty_fasync(int fd, struct file *filp, int on);
+static int tty_fasync(int fd, struct file *filp, int on);
+static void release_tty(struct tty_struct *tty, int idx);
+
+/**
+ * free_tty_struct - free a disused tty
+ * @tty: tty struct to free
+ *
+ * Free the write buffers, tty queue and tty memory itself.
+ *
+ * Locking: none. Must be called after tty is definitely unused
+ */
+
+static void free_tty_struct(struct tty_struct *tty)
+{
+ tty_ldisc_deinit(tty);
+ put_device(tty->dev);
+ kfree(tty->write_buf);
+ tty->magic = 0xDEADDEAD;
+ kfree(tty);
+}
+
+static inline struct tty_struct *file_tty(struct file *file)
+{
+ return ((struct tty_file_private *)file->private_data)->tty;
+}
+
+int tty_alloc_file(struct file *file)
+{
+ struct tty_file_private *priv;
+
+ priv = kmalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ file->private_data = priv;
+
+ return 0;
+}
+
+/* Associate a new file with the tty structure */
+void tty_add_file(struct tty_struct *tty, struct file *file)
+{
+ struct tty_file_private *priv = file->private_data;
+
+ priv->tty = tty;
+ priv->file = file;
+
+ spin_lock(&tty->files_lock);
+ list_add(&priv->list, &tty->tty_files);
+ spin_unlock(&tty->files_lock);
+}
+
+/**
+ * tty_free_file - free file->private_data
+ *
+ * This shall be used only for fail path handling when tty_add_file was not
+ * called yet.
+ */
+void tty_free_file(struct file *file)
+{
+ struct tty_file_private *priv = file->private_data;
+
+ file->private_data = NULL;
+ kfree(priv);
+}
+
+/* Delete file from its tty */
+static void tty_del_file(struct file *file)
+{
+ struct tty_file_private *priv = file->private_data;
+ struct tty_struct *tty = priv->tty;
+
+ spin_lock(&tty->files_lock);
+ list_del(&priv->list);
+ spin_unlock(&tty->files_lock);
+ tty_free_file(file);
+}
+
+/**
+ * tty_name - return tty naming
+ * @tty: tty structure
+ *
+ * Convert a tty structure into a name. The name reflects the kernel
+ * naming policy and if udev is in use may not reflect user space
+ *
+ * Locking: none
+ */
+
+const char *tty_name(const struct tty_struct *tty)
+{
+ if (!tty) /* Hmm. NULL pointer. That's fun. */
+ return "NULL tty";
+ return tty->name;
+}
+
+EXPORT_SYMBOL(tty_name);
+
+const char *tty_driver_name(const struct tty_struct *tty)
+{
+ if (!tty || !tty->driver)
+ return "";
+ return tty->driver->name;
+}
+
+static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
+ const char *routine)
+{
+#ifdef TTY_PARANOIA_CHECK
+ if (!tty) {
+ pr_warn("(%d:%d): %s: NULL tty\n",
+ imajor(inode), iminor(inode), routine);
+ return 1;
+ }
+ if (tty->magic != TTY_MAGIC) {
+ pr_warn("(%d:%d): %s: bad magic number\n",
+ imajor(inode), iminor(inode), routine);
+ return 1;
+ }
+#endif
+ return 0;
+}
+
+/* Caller must hold tty_lock */
+static int check_tty_count(struct tty_struct *tty, const char *routine)
+{
+#ifdef CHECK_TTY_COUNT
+ struct list_head *p;
+ int count = 0, kopen_count = 0;
+
+ spin_lock(&tty->files_lock);
+ list_for_each(p, &tty->tty_files) {
+ count++;
+ }
+ spin_unlock(&tty->files_lock);
+ if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
+ tty->driver->subtype == PTY_TYPE_SLAVE &&
+ tty->link && tty->link->count)
+ count++;
+ if (tty_port_kopened(tty->port))
+ kopen_count++;
+ if (tty->count != (count + kopen_count)) {
+ tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
+ routine, tty->count, count, kopen_count);
+ return (count + kopen_count);
+ }
+#endif
+ return 0;
+}
+
+/**
+ * get_tty_driver - find device of a tty
+ * @dev_t: device identifier
+ * @index: returns the index of the tty
+ *
+ * This routine returns a tty driver structure, given a device number
+ * and also passes back the index number.
+ *
+ * Locking: caller must hold tty_mutex
+ */
+
+static struct tty_driver *get_tty_driver(dev_t device, int *index)
+{
+ struct tty_driver *p;
+
+ list_for_each_entry(p, &tty_drivers, tty_drivers) {
+ dev_t base = MKDEV(p->major, p->minor_start);
+ if (device < base || device >= base + p->num)
+ continue;
+ *index = device - base;
+ return tty_driver_kref_get(p);
+ }
+ return NULL;
+}
+
+/**
+ * tty_dev_name_to_number - return dev_t for device name
+ * @name: user space name of device under /dev
+ * @number: pointer to dev_t that this function will populate
+ *
+ * This function converts device names like ttyS0 or ttyUSB1 into dev_t
+ * like (4, 64) or (188, 1). If no corresponding driver is registered then
+ * the function returns -ENODEV.
+ *
+ * Locking: this acquires tty_mutex to protect the tty_drivers list from
+ * being modified while we are traversing it, and makes sure to
+ * release it before exiting.
+ */
+int tty_dev_name_to_number(const char *name, dev_t *number)
+{
+ struct tty_driver *p;
+ int ret;
+ int index, prefix_length = 0;
+ const char *str;
+
+ for (str = name; *str && !isdigit(*str); str++)
+ ;
+
+ if (!*str)
+ return -EINVAL;
+
+ ret = kstrtoint(str, 10, &index);
+ if (ret)
+ return ret;
+
+ prefix_length = str - name;
+ mutex_lock(&tty_mutex);
+
+ list_for_each_entry(p, &tty_drivers, tty_drivers)
+ if (prefix_length == strlen(p->name) && strncmp(name,
+ p->name, prefix_length) == 0) {
+ if (index < p->num) {
+ *number = MKDEV(p->major, p->minor_start + index);
+ goto out;
+ }
+ }
+
+ /* if here then driver wasn't found */
+ ret = -ENODEV;
+out:
+ mutex_unlock(&tty_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
+
+#ifdef CONFIG_CONSOLE_POLL
+
+/**
+ * tty_find_polling_driver - find device of a polled tty
+ * @name: name string to match
+ * @line: pointer to resulting tty line nr
+ *
+ * This routine returns a tty driver structure, given a name
+ * and the condition that the tty driver is capable of polled
+ * operation.
+ */
+struct tty_driver *tty_find_polling_driver(char *name, int *line)
+{
+ struct tty_driver *p, *res = NULL;
+ int tty_line = 0;
+ int len;
+ char *str, *stp;
+
+ for (str = name; *str; str++)
+ if ((*str >= '0' && *str <= '9') || *str == ',')
+ break;
+ if (!*str)
+ return NULL;
+
+ len = str - name;
+ tty_line = simple_strtoul(str, &str, 10);
+
+ mutex_lock(&tty_mutex);
+ /* Search through the tty devices to look for a match */
+ list_for_each_entry(p, &tty_drivers, tty_drivers) {
+ if (!len || strncmp(name, p->name, len) != 0)
+ continue;
+ stp = str;
+ if (*stp == ',')
+ stp++;
+ if (*stp == '\0')
+ stp = NULL;
+
+ if (tty_line >= 0 && tty_line < p->num && p->ops &&
+ p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
+ res = tty_driver_kref_get(p);
+ *line = tty_line;
+ break;
+ }
+ }
+ mutex_unlock(&tty_mutex);
+
+ return res;
+}
+EXPORT_SYMBOL_GPL(tty_find_polling_driver);
+#endif
+
+static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ return 0;
+}
+
+static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ return -EIO;
+}
+
+/* No kernel lock held - none needed ;) */
+static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
+{
+ return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
+}
+
+static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
+}
+
+static long hung_up_tty_compat_ioctl(struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
+}
+
+static int hung_up_tty_fasync(int fd, struct file *file, int on)
+{
+ return -ENOTTY;
+}
+
+static void tty_show_fdinfo(struct seq_file *m, struct file *file)
+{
+ struct tty_struct *tty = file_tty(file);
+
+ if (tty && tty->ops && tty->ops->show_fdinfo)
+ tty->ops->show_fdinfo(tty, m);
+}
+
+static const struct file_operations tty_fops = {
+ .llseek = no_llseek,
+ .read = tty_read,
+ .write = tty_write,
+ .poll = tty_poll,
+ .unlocked_ioctl = tty_ioctl,
+ .compat_ioctl = tty_compat_ioctl,
+ .open = tty_open,
+ .release = tty_release,
+ .fasync = tty_fasync,
+ .show_fdinfo = tty_show_fdinfo,
+};
+
+static const struct file_operations console_fops = {
+ .llseek = no_llseek,
+ .read = tty_read,
+ .write = redirected_tty_write,
+ .poll = tty_poll,
+ .unlocked_ioctl = tty_ioctl,
+ .compat_ioctl = tty_compat_ioctl,
+ .open = tty_open,
+ .release = tty_release,
+ .fasync = tty_fasync,
+};
+
+static const struct file_operations hung_up_tty_fops = {
+ .llseek = no_llseek,
+ .read = hung_up_tty_read,
+ .write = hung_up_tty_write,
+ .poll = hung_up_tty_poll,
+ .unlocked_ioctl = hung_up_tty_ioctl,
+ .compat_ioctl = hung_up_tty_compat_ioctl,
+ .release = tty_release,
+ .fasync = hung_up_tty_fasync,
+};
+
+static DEFINE_SPINLOCK(redirect_lock);
+static struct file *redirect;
+
+/**
+ * tty_wakeup - request more data
+ * @tty: terminal
+ *
+ * Internal and external helper for wakeups of tty. This function
+ * informs the line discipline if present that the driver is ready
+ * to receive more output data.
+ */
+
+void tty_wakeup(struct tty_struct *tty)
+{
+ struct tty_ldisc *ld;
+
+ if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
+ ld = tty_ldisc_ref(tty);
+ if (ld) {
+ if (ld->ops->write_wakeup)
+ ld->ops->write_wakeup(tty);
+ tty_ldisc_deref(ld);
+ }
+ }
+ wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
+}
+
+EXPORT_SYMBOL_GPL(tty_wakeup);
+
+/**
+ * __tty_hangup - actual handler for hangup events
+ * @work: tty device
+ *
+ * This can be called by a "kworker" kernel thread. That is process
+ * synchronous but doesn't hold any locks, so we need to make sure we
+ * have the appropriate locks for what we're doing.
+ *
+ * The hangup event clears any pending redirections onto the hung up
+ * device. It ensures future writes will error and it does the needed
+ * line discipline hangup and signal delivery. The tty object itself
+ * remains intact.
+ *
+ * Locking:
+ * BTM
+ * redirect lock for undoing redirection
+ * file list lock for manipulating list of ttys
+ * tty_ldiscs_lock from called functions
+ * termios_rwsem resetting termios data
+ * tasklist_lock to walk task list for hangup event
+ * ->siglock to protect ->signal/->sighand
+ */
+static void __tty_hangup(struct tty_struct *tty, int exit_session)
+{
+ struct file *cons_filp = NULL;
+ struct file *filp, *f = NULL;
+ struct tty_file_private *priv;
+ int closecount = 0, n;
+ int refs;
+
+ if (!tty)
+ return;
+
+
+ spin_lock(&redirect_lock);
+ if (redirect && file_tty(redirect) == tty) {
+ f = redirect;
+ redirect = NULL;
+ }
+ spin_unlock(&redirect_lock);
+
+ tty_lock(tty);
+
+ if (test_bit(TTY_HUPPED, &tty->flags)) {
+ tty_unlock(tty);
+ return;
+ }
+
+ /*
+ * Some console devices aren't actually hung up for technical and
+ * historical reasons, which can lead to indefinite interruptible
+ * sleep in n_tty_read(). The following explicitly tells
+ * n_tty_read() to abort readers.
+ */
+ set_bit(TTY_HUPPING, &tty->flags);
+
+ /* inuse_filps is protected by the single tty lock,
+ this really needs to change if we want to flush the
+ workqueue with the lock held */
+ check_tty_count(tty, "tty_hangup");
+
+ spin_lock(&tty->files_lock);
+ /* This breaks for file handles being sent over AF_UNIX sockets ? */
+ list_for_each_entry(priv, &tty->tty_files, list) {
+ filp = priv->file;
+ if (filp->f_op->write == redirected_tty_write)
+ cons_filp = filp;
+ if (filp->f_op->write != tty_write)
+ continue;
+ closecount++;
+ __tty_fasync(-1, filp, 0); /* can't block */
+ filp->f_op = &hung_up_tty_fops;
+ }
+ spin_unlock(&tty->files_lock);
+
+ refs = tty_signal_session_leader(tty, exit_session);
+ /* Account for the p->signal references we killed */
+ while (refs--)
+ tty_kref_put(tty);
+
+ tty_ldisc_hangup(tty, cons_filp != NULL);
+
+ spin_lock_irq(&tty->ctrl_lock);
+ clear_bit(TTY_THROTTLED, &tty->flags);
+ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+ put_pid(tty->session);
+ put_pid(tty->pgrp);
+ tty->session = NULL;
+ tty->pgrp = NULL;
+ tty->ctrl_status = 0;
+ spin_unlock_irq(&tty->ctrl_lock);
+
+ /*
+ * If one of the devices matches a console pointer, we
+ * cannot just call hangup() because that will cause
+ * tty->count and state->count to go out of sync.
+ * So we just call close() the right number of times.
+ */
+ if (cons_filp) {
+ if (tty->ops->close)
+ for (n = 0; n < closecount; n++)
+ tty->ops->close(tty, cons_filp);
+ } else if (tty->ops->hangup)
+ tty->ops->hangup(tty);
+ /*
+ * We don't want to have driver/ldisc interactions beyond the ones
+ * we did here. The driver layer expects no calls after ->hangup()
+ * from the ldisc side, which is now guaranteed.
+ */
+ set_bit(TTY_HUPPED, &tty->flags);
+ clear_bit(TTY_HUPPING, &tty->flags);
+ tty_unlock(tty);
+
+ if (f)
+ fput(f);
+}
+
+static void do_tty_hangup(struct work_struct *work)
+{
+ struct tty_struct *tty =
+ container_of(work, struct tty_struct, hangup_work);
+
+ __tty_hangup(tty, 0);
+}
+
+/**
+ * tty_hangup - trigger a hangup event
+ * @tty: tty to hangup
+ *
+ * A carrier loss (virtual or otherwise) has occurred on this like
+ * schedule a hangup sequence to run after this event.
+ */
+
+void tty_hangup(struct tty_struct *tty)
+{
+ tty_debug_hangup(tty, "hangup\n");
+ schedule_work(&tty->hangup_work);
+}
+
+EXPORT_SYMBOL(tty_hangup);
+
+/**
+ * tty_vhangup - process vhangup
+ * @tty: tty to hangup
+ *
+ * The user has asked via system call for the terminal to be hung up.
+ * We do this synchronously so that when the syscall returns the process
+ * is complete. That guarantee is necessary for security reasons.
+ */
+
+void tty_vhangup(struct tty_struct *tty)
+{
+ tty_debug_hangup(tty, "vhangup\n");
+ __tty_hangup(tty, 0);
+}
+
+EXPORT_SYMBOL(tty_vhangup);
+
+
+/**
+ * tty_vhangup_self - process vhangup for own ctty
+ *
+ * Perform a vhangup on the current controlling tty
+ */
+
+void tty_vhangup_self(void)
+{
+ struct tty_struct *tty;
+
+ tty = get_current_tty();
+ if (tty) {
+ tty_vhangup(tty);
+ tty_kref_put(tty);
+ }
+}
+
+/**
+ * tty_vhangup_session - hangup session leader exit
+ * @tty: tty to hangup
+ *
+ * The session leader is exiting and hanging up its controlling terminal.
+ * Every process in the foreground process group is signalled SIGHUP.
+ *
+ * We do this synchronously so that when the syscall returns the process
+ * is complete. That guarantee is necessary for security reasons.
+ */
+
+void tty_vhangup_session(struct tty_struct *tty)
+{
+ tty_debug_hangup(tty, "session hangup\n");
+ __tty_hangup(tty, 1);
+}
+
+/**
+ * tty_hung_up_p - was tty hung up
+ * @filp: file pointer of tty
+ *
+ * Return true if the tty has been subject to a vhangup or a carrier
+ * loss
+ */
+
+int tty_hung_up_p(struct file *filp)
+{
+ return (filp && filp->f_op == &hung_up_tty_fops);
+}
+
+EXPORT_SYMBOL(tty_hung_up_p);
+
+/**
+ * stop_tty - propagate flow control
+ * @tty: tty to stop
+ *
+ * Perform flow control to the driver. May be called
+ * on an already stopped device and will not re-call the driver
+ * method.
+ *
+ * This functionality is used by both the line disciplines for
+ * halting incoming flow and by the driver. It may therefore be
+ * called from any context, may be under the tty atomic_write_lock
+ * but not always.
+ *
+ * Locking:
+ * flow_lock
+ */
+
+void __stop_tty(struct tty_struct *tty)
+{
+ if (tty->stopped)
+ return;
+ tty->stopped = 1;
+ if (tty->ops->stop)
+ tty->ops->stop(tty);
+}
+
+void stop_tty(struct tty_struct *tty)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&tty->flow_lock, flags);
+ __stop_tty(tty);
+ spin_unlock_irqrestore(&tty->flow_lock, flags);
+}
+EXPORT_SYMBOL(stop_tty);
+
+/**
+ * start_tty - propagate flow control
+ * @tty: tty to start
+ *
+ * Start a tty that has been stopped if at all possible. If this
+ * tty was previous stopped and is now being started, the driver
+ * start method is invoked and the line discipline woken.
+ *
+ * Locking:
+ * flow_lock
+ */
+
+void __start_tty(struct tty_struct *tty)
+{
+ if (!tty->stopped || tty->flow_stopped)
+ return;
+ tty->stopped = 0;
+ if (tty->ops->start)
+ tty->ops->start(tty);
+ tty_wakeup(tty);
+}
+
+void start_tty(struct tty_struct *tty)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&tty->flow_lock, flags);
+ __start_tty(tty);
+ spin_unlock_irqrestore(&tty->flow_lock, flags);
+}
+EXPORT_SYMBOL(start_tty);
+
+static void tty_update_time(struct timespec64 *time)
+{
+ time64_t sec = ktime_get_real_seconds();
+
+ /*
+ * We only care if the two values differ in anything other than the
+ * lower three bits (i.e every 8 seconds). If so, then we can update
+ * the time of the tty device, otherwise it could be construded as a
+ * security leak to let userspace know the exact timing of the tty.
+ */
+ if ((sec ^ time->tv_sec) & ~7)
+ time->tv_sec = sec;
+}
+
+/**
+ * tty_read - read method for tty device files
+ * @file: pointer to tty file
+ * @buf: user buffer
+ * @count: size of user buffer
+ * @ppos: unused
+ *
+ * Perform the read system call function on this terminal device. Checks
+ * for hung up devices before calling the line discipline method.
+ *
+ * Locking:
+ * Locks the line discipline internally while needed. Multiple
+ * read calls may be outstanding in parallel.
+ */
+
+static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ int i;
+ struct inode *inode = file_inode(file);
+ struct tty_struct *tty = file_tty(file);
+ struct tty_ldisc *ld;
+
+ if (tty_paranoia_check(tty, inode, "tty_read"))
+ return -EIO;
+ if (!tty || tty_io_error(tty))
+ return -EIO;
+
+ /* We want to wait for the line discipline to sort out in this
+ situation */
+ ld = tty_ldisc_ref_wait(tty);
+ if (!ld)
+ return hung_up_tty_read(file, buf, count, ppos);
+ if (ld->ops->read)
+ i = ld->ops->read(tty, file, buf, count);
+ else
+ i = -EIO;
+ tty_ldisc_deref(ld);
+
+ if (i > 0)
+ tty_update_time(&inode->i_atime);
+
+ return i;
+}
+
+static void tty_write_unlock(struct tty_struct *tty)
+{
+ mutex_unlock(&tty->atomic_write_lock);
+ wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
+}
+
+static int tty_write_lock(struct tty_struct *tty, int ndelay)
+{
+ if (!mutex_trylock(&tty->atomic_write_lock)) {
+ if (ndelay)
+ return -EAGAIN;
+ if (mutex_lock_interruptible(&tty->atomic_write_lock))
+ return -ERESTARTSYS;
+ }
+ return 0;
+}
+
+/*
+ * Split writes up in sane blocksizes to avoid
+ * denial-of-service type attacks
+ */
+static inline ssize_t do_tty_write(
+ ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
+ struct tty_struct *tty,
+ struct file *file,
+ const char __user *buf,
+ size_t count)
+{
+ ssize_t ret, written = 0;
+ unsigned int chunk;
+
+ ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * We chunk up writes into a temporary buffer. This
+ * simplifies low-level drivers immensely, since they
+ * don't have locking issues and user mode accesses.
+ *
+ * But if TTY_NO_WRITE_SPLIT is set, we should use a
+ * big chunk-size..
+ *
+ * The default chunk-size is 2kB, because the NTTY
+ * layer has problems with bigger chunks. It will
+ * claim to be able to handle more characters than
+ * it actually does.
+ *
+ * FIXME: This can probably go away now except that 64K chunks
+ * are too likely to fail unless switched to vmalloc...
+ */
+ chunk = 2048;
+ if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
+ chunk = 65536;
+ if (count < chunk)
+ chunk = count;
+
+ /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
+ if (tty->write_cnt < chunk) {
+ unsigned char *buf_chunk;
+
+ if (chunk < 1024)
+ chunk = 1024;
+
+ buf_chunk = kmalloc(chunk, GFP_KERNEL);
+ if (!buf_chunk) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ kfree(tty->write_buf);
+ tty->write_cnt = chunk;
+ tty->write_buf = buf_chunk;
+ }
+
+ /* Do the write .. */
+ for (;;) {
+ size_t size = count;
+ if (size > chunk)
+ size = chunk;
+ ret = -EFAULT;
+ if (copy_from_user(tty->write_buf, buf, size))
+ break;
+ ret = write(tty, file, tty->write_buf, size);
+ if (ret <= 0)
+ break;
+ written += ret;
+ buf += ret;
+ count -= ret;
+ if (!count)
+ break;
+ ret = -ERESTARTSYS;
+ if (signal_pending(current))
+ break;
+ cond_resched();
+ }
+ if (written) {
+ tty_update_time(&file_inode(file)->i_mtime);
+ ret = written;
+ }
+out:
+ tty_write_unlock(tty);
+ return ret;
+}
+
+/**
+ * tty_write_message - write a message to a certain tty, not just the console.
+ * @tty: the destination tty_struct
+ * @msg: the message to write
+ *
+ * This is used for messages that need to be redirected to a specific tty.
+ * We don't put it into the syslog queue right now maybe in the future if
+ * really needed.
+ *
+ * We must still hold the BTM and test the CLOSING flag for the moment.
+ */
+
+void tty_write_message(struct tty_struct *tty, char *msg)
+{
+ if (tty) {
+ mutex_lock(&tty->atomic_write_lock);
+ tty_lock(tty);
+ if (tty->ops->write && tty->count > 0)
+ tty->ops->write(tty, msg, strlen(msg));
+ tty_unlock(tty);
+ tty_write_unlock(tty);
+ }
+ return;
+}
+
+
+/**
+ * tty_write - write method for tty device file
+ * @file: tty file pointer
+ * @buf: user data to write
+ * @count: bytes to write
+ * @ppos: unused
+ *
+ * Write data to a tty device via the line discipline.
+ *
+ * Locking:
+ * Locks the line discipline as required
+ * Writes to the tty driver are serialized by the atomic_write_lock
+ * and are then processed in chunks to the device. The line discipline
+ * write method will not be invoked in parallel for each device.
+ */
+
+static ssize_t tty_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct tty_struct *tty = file_tty(file);
+ struct tty_ldisc *ld;
+ ssize_t ret;
+
+ if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
+ return -EIO;
+ if (!tty || !tty->ops->write || tty_io_error(tty))
+ return -EIO;
+ /* Short term debug to catch buggy drivers */
+ if (tty->ops->write_room == NULL)
+ tty_err(tty, "missing write_room method\n");
+ ld = tty_ldisc_ref_wait(tty);
+ if (!ld)
+ return hung_up_tty_write(file, buf, count, ppos);
+ if (!ld->ops->write)
+ ret = -EIO;
+ else
+ ret = do_tty_write(ld->ops->write, tty, file, buf, count);
+ tty_ldisc_deref(ld);
+ return ret;
+}
+
+ssize_t redirected_tty_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct file *p = NULL;
+
+ spin_lock(&redirect_lock);
+ if (redirect)
+ p = get_file(redirect);
+ spin_unlock(&redirect_lock);
+
+ if (p) {
+ ssize_t res;
+ res = vfs_write(p, buf, count, &p->f_pos);
+ fput(p);
+ return res;
+ }
+ return tty_write(file, buf, count, ppos);
+}
+
+/**
+ * tty_send_xchar - send priority character
+ *
+ * Send a high priority character to the tty even if stopped
+ *
+ * Locking: none for xchar method, write ordering for write method.
+ */
+
+int tty_send_xchar(struct tty_struct *tty, char ch)
+{
+ int was_stopped = tty->stopped;
+
+ if (tty->ops->send_xchar) {
+ down_read(&tty->termios_rwsem);
+ tty->ops->send_xchar(tty, ch);
+ up_read(&tty->termios_rwsem);
+ return 0;
+ }
+
+ if (tty_write_lock(tty, 0) < 0)
+ return -ERESTARTSYS;
+
+ down_read(&tty->termios_rwsem);
+ if (was_stopped)
+ start_tty(tty);
+ tty->ops->write(tty, &ch, 1);
+ if (was_stopped)
+ stop_tty(tty);
+ up_read(&tty->termios_rwsem);
+ tty_write_unlock(tty);
+ return 0;
+}
+
+static char ptychar[] = "pqrstuvwxyzabcde";
+
+/**
+ * pty_line_name - generate name for a pty
+ * @driver: the tty driver in use
+ * @index: the minor number
+ * @p: output buffer of at least 6 bytes
+ *
+ * Generate a name from a driver reference and write it to the output
+ * buffer.
+ *
+ * Locking: None
+ */
+static void pty_line_name(struct tty_driver *driver, int index, char *p)
+{
+ int i = index + driver->name_base;
+ /* ->name is initialized to "ttyp", but "tty" is expected */
+ sprintf(p, "%s%c%x",
+ driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
+ ptychar[i >> 4 & 0xf], i & 0xf);
+}
+
+/**
+ * tty_line_name - generate name for a tty
+ * @driver: the tty driver in use
+ * @index: the minor number
+ * @p: output buffer of at least 7 bytes
+ *
+ * Generate a name from a driver reference and write it to the output
+ * buffer.
+ *
+ * Locking: None
+ */
+static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
+{
+ if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
+ return sprintf(p, "%s", driver->name);
+ else
+ return sprintf(p, "%s%d", driver->name,
+ index + driver->name_base);
+}
+
+/**
+ * tty_driver_lookup_tty() - find an existing tty, if any
+ * @driver: the driver for the tty
+ * @idx: the minor number
+ *
+ * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
+ * driver lookup() method returns an error.
+ *
+ * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
+ */
+static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
+ struct file *file, int idx)
+{
+ struct tty_struct *tty;
+
+ if (driver->ops->lookup)
+ if (!file)
+ tty = ERR_PTR(-EIO);
+ else
+ tty = driver->ops->lookup(driver, file, idx);
+ else
+ tty = driver->ttys[idx];
+
+ if (!IS_ERR(tty))
+ tty_kref_get(tty);
+ return tty;
+}
+
+/**
+ * tty_init_termios - helper for termios setup
+ * @tty: the tty to set up
+ *
+ * Initialise the termios structures for this tty. Thus runs under
+ * the tty_mutex currently so we can be relaxed about ordering.
+ */
+
+void tty_init_termios(struct tty_struct *tty)
+{
+ struct ktermios *tp;
+ int idx = tty->index;
+
+ if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
+ tty->termios = tty->driver->init_termios;
+ else {
+ /* Check for lazy saved data */
+ tp = tty->driver->termios[idx];
+ if (tp != NULL) {
+ tty->termios = *tp;
+ tty->termios.c_line = tty->driver->init_termios.c_line;
+ } else
+ tty->termios = tty->driver->init_termios;
+ }
+ /* Compatibility until drivers always set this */
+ tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
+ tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
+}
+EXPORT_SYMBOL_GPL(tty_init_termios);
+
+int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+ tty_init_termios(tty);
+ tty_driver_kref_get(driver);
+ tty->count++;
+ driver->ttys[tty->index] = tty;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tty_standard_install);
+
+/**
+ * tty_driver_install_tty() - install a tty entry in the driver
+ * @driver: the driver for the tty
+ * @tty: the tty
+ *
+ * Install a tty object into the driver tables. The tty->index field
+ * will be set by the time this is called. This method is responsible
+ * for ensuring any need additional structures are allocated and
+ * configured.
+ *
+ * Locking: tty_mutex for now
+ */
+static int tty_driver_install_tty(struct tty_driver *driver,
+ struct tty_struct *tty)
+{
+ return driver->ops->install ? driver->ops->install(driver, tty) :
+ tty_standard_install(driver, tty);
+}
+
+/**
+ * tty_driver_remove_tty() - remove a tty from the driver tables
+ * @driver: the driver for the tty
+ * @idx: the minor number
+ *
+ * Remvoe a tty object from the driver tables. The tty->index field
+ * will be set by the time this is called.
+ *
+ * Locking: tty_mutex for now
+ */
+static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
+{
+ if (driver->ops->remove)
+ driver->ops->remove(driver, tty);
+ else
+ driver->ttys[tty->index] = NULL;
+}
+
+/*
+ * tty_reopen() - fast re-open of an open tty
+ * @tty - the tty to open
+ *
+ * Return 0 on success, -errno on error.
+ * Re-opens on master ptys are not allowed and return -EIO.
+ *
+ * Locking: Caller must hold tty_lock
+ */
+static int tty_reopen(struct tty_struct *tty)
+{
+ struct tty_driver *driver = tty->driver;
+ int retval;
+
+ if (driver->type == TTY_DRIVER_TYPE_PTY &&
+ driver->subtype == PTY_TYPE_MASTER)
+ return -EIO;
+
+ if (!tty->count)
+ return -EAGAIN;
+
+ if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
+ return -EBUSY;
+
+ tty->count++;
+
+ if (tty->ldisc)
+ return 0;
+
+ retval = tty_ldisc_reinit(tty, tty->termios.c_line);
+ if (retval)
+ tty->count--;
+
+ return retval;
+}
+
+/**
+ * tty_init_dev - initialise a tty device
+ * @driver: tty driver we are opening a device on
+ * @idx: device index
+ * @ret_tty: returned tty structure
+ *
+ * Prepare a tty device. This may not be a "new" clean device but
+ * could also be an active device. The pty drivers require special
+ * handling because of this.
+ *
+ * Locking:
+ * The function is called under the tty_mutex, which
+ * protects us from the tty struct or driver itself going away.
+ *
+ * On exit the tty device has the line discipline attached and
+ * a reference count of 1. If a pair was created for pty/tty use
+ * and the other was a pty master then it too has a reference count of 1.
+ *
+ * WSH 06/09/97: Rewritten to remove races and properly clean up after a
+ * failed open. The new code protects the open with a mutex, so it's
+ * really quite straightforward. The mutex locking can probably be
+ * relaxed for the (most common) case of reopening a tty.
+ */
+
+struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
+{
+ struct tty_struct *tty;
+ int retval;
+
+ /*
+ * First time open is complex, especially for PTY devices.
+ * This code guarantees that either everything succeeds and the
+ * TTY is ready for operation, or else the table slots are vacated
+ * and the allocated memory released. (Except that the termios
+ * may be retained.)
+ */
+
+ if (!try_module_get(driver->owner))
+ return ERR_PTR(-ENODEV);
+
+ tty = alloc_tty_struct(driver, idx);
+ if (!tty) {
+ retval = -ENOMEM;
+ goto err_module_put;
+ }
+
+ tty_lock(tty);
+ retval = tty_driver_install_tty(driver, tty);
+ if (retval < 0)
+ goto err_free_tty;
+
+ if (!tty->port)
+ tty->port = driver->ports[idx];
+
+ WARN_RATELIMIT(!tty->port,
+ "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
+ __func__, tty->driver->name);
+
+ retval = tty_ldisc_lock(tty, 5 * HZ);
+ if (retval)
+ goto err_release_lock;
+ tty->port->itty = tty;
+
+ /*
+ * Structures all installed ... call the ldisc open routines.
+ * If we fail here just call release_tty to clean up. No need
+ * to decrement the use counts, as release_tty doesn't care.
+ */
+ retval = tty_ldisc_setup(tty, tty->link);
+ if (retval)
+ goto err_release_tty;
+ tty_ldisc_unlock(tty);
+ /* Return the tty locked so that it cannot vanish under the caller */
+ return tty;
+
+err_free_tty:
+ tty_unlock(tty);
+ free_tty_struct(tty);
+err_module_put:
+ module_put(driver->owner);
+ return ERR_PTR(retval);
+
+ /* call the tty release_tty routine to clean out this slot */
+err_release_tty:
+ tty_ldisc_unlock(tty);
+ tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
+ retval, idx);
+err_release_lock:
+ tty_unlock(tty);
+ release_tty(tty, idx);
+ return ERR_PTR(retval);
+}
+
+/**
+ * tty_save_termios() - save tty termios data in driver table
+ * @tty: tty whose termios data to save
+ *
+ * Locking: Caller guarantees serialisation with tty_init_termios().
+ */
+void tty_save_termios(struct tty_struct *tty)
+{
+ struct ktermios *tp;
+ int idx = tty->index;
+
+ /* If the port is going to reset then it has no termios to save */
+ if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
+ return;
+
+ /* Stash the termios data */
+ tp = tty->driver->termios[idx];
+ if (tp == NULL) {
+ tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
+ if (tp == NULL)
+ return;
+ tty->driver->termios[idx] = tp;
+ }
+ *tp = tty->termios;
+}
+EXPORT_SYMBOL_GPL(tty_save_termios);
+
+/**
+ * tty_flush_works - flush all works of a tty/pty pair
+ * @tty: tty device to flush works for (or either end of a pty pair)
+ *
+ * Sync flush all works belonging to @tty (and the 'other' tty).
+ */
+static void tty_flush_works(struct tty_struct *tty)
+{
+ flush_work(&tty->SAK_work);
+ flush_work(&tty->hangup_work);
+ if (tty->link) {
+ flush_work(&tty->link->SAK_work);
+ flush_work(&tty->link->hangup_work);
+ }
+}
+
+/**
+ * release_one_tty - release tty structure memory
+ * @kref: kref of tty we are obliterating
+ *
+ * Releases memory associated with a tty structure, and clears out the
+ * driver table slots. This function is called when a device is no longer
+ * in use. It also gets called when setup of a device fails.
+ *
+ * Locking:
+ * takes the file list lock internally when working on the list
+ * of ttys that the driver keeps.
+ *
+ * This method gets called from a work queue so that the driver private
+ * cleanup ops can sleep (needed for USB at least)
+ */
+static void release_one_tty(struct work_struct *work)
+{
+ struct tty_struct *tty =
+ container_of(work, struct tty_struct, hangup_work);
+ struct tty_driver *driver = tty->driver;
+ struct module *owner = driver->owner;
+
+ if (tty->ops->cleanup)
+ tty->ops->cleanup(tty);
+
+ tty->magic = 0;
+ tty_driver_kref_put(driver);
+ module_put(owner);
+
+ spin_lock(&tty->files_lock);
+ list_del_init(&tty->tty_files);
+ spin_unlock(&tty->files_lock);
+
+ put_pid(tty->pgrp);
+ put_pid(tty->session);
+ free_tty_struct(tty);
+}
+
+static void queue_release_one_tty(struct kref *kref)
+{
+ struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
+
+ /* The hangup queue is now free so we can reuse it rather than
+ waste a chunk of memory for each port */
+ INIT_WORK(&tty->hangup_work, release_one_tty);
+ schedule_work(&tty->hangup_work);
+}
+
+/**
+ * tty_kref_put - release a tty kref
+ * @tty: tty device
+ *
+ * Release a reference to a tty device and if need be let the kref
+ * layer destruct the object for us
+ */
+
+void tty_kref_put(struct tty_struct *tty)
+{
+ if (tty)
+ kref_put(&tty->kref, queue_release_one_tty);
+}
+EXPORT_SYMBOL(tty_kref_put);
+
+/**
+ * release_tty - release tty structure memory
+ *
+ * Release both @tty and a possible linked partner (think pty pair),
+ * and decrement the refcount of the backing module.
+ *
+ * Locking:
+ * tty_mutex
+ * takes the file list lock internally when working on the list
+ * of ttys that the driver keeps.
+ *
+ */
+static void release_tty(struct tty_struct *tty, int idx)
+{
+ /* This should always be true but check for the moment */
+ WARN_ON(tty->index != idx);
+ WARN_ON(!mutex_is_locked(&tty_mutex));
+ if (tty->ops->shutdown)
+ tty->ops->shutdown(tty);
+ tty_save_termios(tty);
+ tty_driver_remove_tty(tty->driver, tty);
+ tty->port->itty = NULL;
+ if (tty->link)
+ tty->link->port->itty = NULL;
+ tty_buffer_cancel_work(tty->port);
+ if (tty->link)
+ tty_buffer_cancel_work(tty->link->port);
+
+ tty_kref_put(tty->link);
+ tty_kref_put(tty);
+}
+
+/**
+ * tty_release_checks - check a tty before real release
+ * @tty: tty to check
+ * @o_tty: link of @tty (if any)
+ * @idx: index of the tty
+ *
+ * Performs some paranoid checking before true release of the @tty.
+ * This is a no-op unless TTY_PARANOIA_CHECK is defined.
+ */
+static int tty_release_checks(struct tty_struct *tty, int idx)
+{
+#ifdef TTY_PARANOIA_CHECK
+ if (idx < 0 || idx >= tty->driver->num) {
+ tty_debug(tty, "bad idx %d\n", idx);
+ return -1;
+ }
+
+ /* not much to check for devpts */
+ if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
+ return 0;
+
+ if (tty != tty->driver->ttys[idx]) {
+ tty_debug(tty, "bad driver table[%d] = %p\n",
+ idx, tty->driver->ttys[idx]);
+ return -1;
+ }
+ if (tty->driver->other) {
+ struct tty_struct *o_tty = tty->link;
+
+ if (o_tty != tty->driver->other->ttys[idx]) {
+ tty_debug(tty, "bad other table[%d] = %p\n",
+ idx, tty->driver->other->ttys[idx]);
+ return -1;
+ }
+ if (o_tty->link != tty) {
+ tty_debug(tty, "bad link = %p\n", o_tty->link);
+ return -1;
+ }
+ }
+#endif
+ return 0;
+}
+
+/**
+ * tty_kclose - closes tty opened by tty_kopen
+ * @tty: tty device
+ *
+ * Performs the final steps to release and free a tty device. It is the
+ * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
+ * flag on tty->port.
+ */
+void tty_kclose(struct tty_struct *tty)
+{
+ /*
+ * Ask the line discipline code to release its structures
+ */
+ tty_ldisc_release(tty);
+
+ /* Wait for pending work before tty destruction commmences */
+ tty_flush_works(tty);
+
+ tty_debug_hangup(tty, "freeing structure\n");
+ /*
+ * The release_tty function takes care of the details of clearing
+ * the slots and preserving the termios structure. The tty_unlock_pair
+ * should be safe as we keep a kref while the tty is locked (so the
+ * unlock never unlocks a freed tty).
+ */
+ mutex_lock(&tty_mutex);
+ tty_port_set_kopened(tty->port, 0);
+ release_tty(tty, tty->index);
+ mutex_unlock(&tty_mutex);
+}
+EXPORT_SYMBOL_GPL(tty_kclose);
+
+/**
+ * tty_release_struct - release a tty struct
+ * @tty: tty device
+ * @idx: index of the tty
+ *
+ * Performs the final steps to release and free a tty device. It is
+ * roughly the reverse of tty_init_dev.
+ */
+void tty_release_struct(struct tty_struct *tty, int idx)
+{
+ /*
+ * Ask the line discipline code to release its structures
+ */
+ tty_ldisc_release(tty);
+
+ /* Wait for pending work before tty destruction commmences */
+ tty_flush_works(tty);
+
+ tty_debug_hangup(tty, "freeing structure\n");
+ /*
+ * The release_tty function takes care of the details of clearing
+ * the slots and preserving the termios structure. The tty_unlock_pair
+ * should be safe as we keep a kref while the tty is locked (so the
+ * unlock never unlocks a freed tty).
+ */
+ mutex_lock(&tty_mutex);
+ release_tty(tty, idx);
+ mutex_unlock(&tty_mutex);
+}
+EXPORT_SYMBOL_GPL(tty_release_struct);
+
+/**
+ * tty_release - vfs callback for close
+ * @inode: inode of tty
+ * @filp: file pointer for handle to tty
+ *
+ * Called the last time each file handle is closed that references
+ * this tty. There may however be several such references.
+ *
+ * Locking:
+ * Takes bkl. See tty_release_dev
+ *
+ * Even releasing the tty structures is a tricky business.. We have
+ * to be very careful that the structures are all released at the
+ * same time, as interrupts might otherwise get the wrong pointers.
+ *
+ * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
+ * lead to double frees or releasing memory still in use.
+ */
+
+int tty_release(struct inode *inode, struct file *filp)
+{
+ struct tty_struct *tty = file_tty(filp);
+ struct tty_struct *o_tty = NULL;
+ int do_sleep, final;
+ int idx;
+ long timeout = 0;
+ int once = 1;
+
+ if (tty_paranoia_check(tty, inode, __func__))
+ return 0;
+
+ tty_lock(tty);
+ check_tty_count(tty, __func__);
+
+ __tty_fasync(-1, filp, 0);
+
+ idx = tty->index;
+ if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
+ tty->driver->subtype == PTY_TYPE_MASTER)
+ o_tty = tty->link;
+
+ if (tty_release_checks(tty, idx)) {
+ tty_unlock(tty);
+ return 0;
+ }
+
+ tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
+
+ if (tty->ops->close)
+ tty->ops->close(tty, filp);
+
+ /* If tty is pty master, lock the slave pty (stable lock order) */
+ tty_lock_slave(o_tty);
+
+ /*
+ * Sanity check: if tty->count is going to zero, there shouldn't be
+ * any waiters on tty->read_wait or tty->write_wait. We test the
+ * wait queues and kick everyone out _before_ actually starting to
+ * close. This ensures that we won't block while releasing the tty
+ * structure.
+ *
+ * The test for the o_tty closing is necessary, since the master and
+ * slave sides may close in any order. If the slave side closes out
+ * first, its count will be one, since the master side holds an open.
+ * Thus this test wouldn't be triggered at the time the slave closed,
+ * so we do it now.
+ */
+ while (1) {
+ do_sleep = 0;
+
+ if (tty->count <= 1) {
+ if (waitqueue_active(&tty->read_wait)) {
+ wake_up_poll(&tty->read_wait, EPOLLIN);
+ do_sleep++;
+ }
+ if (waitqueue_active(&tty->write_wait)) {
+ wake_up_poll(&tty->write_wait, EPOLLOUT);
+ do_sleep++;
+ }
+ }
+ if (o_tty && o_tty->count <= 1) {
+ if (waitqueue_active(&o_tty->read_wait)) {
+ wake_up_poll(&o_tty->read_wait, EPOLLIN);
+ do_sleep++;
+ }
+ if (waitqueue_active(&o_tty->write_wait)) {
+ wake_up_poll(&o_tty->write_wait, EPOLLOUT);
+ do_sleep++;
+ }
+ }
+ if (!do_sleep)
+ break;
+
+ if (once) {
+ once = 0;
+ tty_warn(tty, "read/write wait queue active!\n");
+ }
+ schedule_timeout_killable(timeout);
+ if (timeout < 120 * HZ)
+ timeout = 2 * timeout + 1;
+ else
+ timeout = MAX_SCHEDULE_TIMEOUT;
+ }
+
+ if (o_tty) {
+ if (--o_tty->count < 0) {
+ tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
+ o_tty->count = 0;
+ }
+ }
+ if (--tty->count < 0) {
+ tty_warn(tty, "bad tty->count (%d)\n", tty->count);
+ tty->count = 0;
+ }
+
+ /*
+ * We've decremented tty->count, so we need to remove this file
+ * descriptor off the tty->tty_files list; this serves two
+ * purposes:
+ * - check_tty_count sees the correct number of file descriptors
+ * associated with this tty.
+ * - do_tty_hangup no longer sees this file descriptor as
+ * something that needs to be handled for hangups.
+ */
+ tty_del_file(filp);
+
+ /*
+ * Perform some housekeeping before deciding whether to return.
+ *
+ * If _either_ side is closing, make sure there aren't any
+ * processes that still think tty or o_tty is their controlling
+ * tty.
+ */
+ if (!tty->count) {
+ read_lock(&tasklist_lock);
+ session_clear_tty(tty->session);
+ if (o_tty)
+ session_clear_tty(o_tty->session);
+ read_unlock(&tasklist_lock);
+ }
+
+ /* check whether both sides are closing ... */
+ final = !tty->count && !(o_tty && o_tty->count);
+
+ tty_unlock_slave(o_tty);
+ tty_unlock(tty);
+
+ /* At this point, the tty->count == 0 should ensure a dead tty
+ cannot be re-opened by a racing opener */
+
+ if (!final)
+ return 0;
+
+ tty_debug_hangup(tty, "final close\n");
+
+ tty_release_struct(tty, idx);
+ return 0;
+}
+
+/**
+ * tty_open_current_tty - get locked tty of current task
+ * @device: device number
+ * @filp: file pointer to tty
+ * @return: locked tty of the current task iff @device is /dev/tty
+ *
+ * Performs a re-open of the current task's controlling tty.
+ *
+ * We cannot return driver and index like for the other nodes because
+ * devpts will not work then. It expects inodes to be from devpts FS.
+ */
+static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
+{
+ struct tty_struct *tty;
+ int retval;
+
+ if (device != MKDEV(TTYAUX_MAJOR, 0))
+ return NULL;
+
+ tty = get_current_tty();
+ if (!tty)
+ return ERR_PTR(-ENXIO);
+
+ filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
+ /* noctty = 1; */
+ tty_lock(tty);
+ tty_kref_put(tty); /* safe to drop the kref now */
+
+ retval = tty_reopen(tty);
+ if (retval < 0) {
+ tty_unlock(tty);
+ tty = ERR_PTR(retval);
+ }
+ return tty;
+}
+
+/**
+ * tty_lookup_driver - lookup a tty driver for a given device file
+ * @device: device number
+ * @filp: file pointer to tty
+ * @index: index for the device in the @return driver
+ * @return: driver for this inode (with increased refcount)
+ *
+ * If @return is not erroneous, the caller is responsible to decrement the
+ * refcount by tty_driver_kref_put.
+ *
+ * Locking: tty_mutex protects get_tty_driver
+ */
+static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
+ int *index)
+{
+ struct tty_driver *driver;
+
+ switch (device) {
+#ifdef CONFIG_VT
+ case MKDEV(TTY_MAJOR, 0): {
+ extern struct tty_driver *console_driver;
+ driver = tty_driver_kref_get(console_driver);
+ *index = fg_console;
+ break;
+ }
+#endif
+ case MKDEV(TTYAUX_MAJOR, 1): {
+ struct tty_driver *console_driver = console_device(index);
+ if (console_driver) {
+ driver = tty_driver_kref_get(console_driver);
+ if (driver && filp) {
+ /* Don't let /dev/console block */
+ filp->f_flags |= O_NONBLOCK;
+ break;
+ }
+ }
+ return ERR_PTR(-ENODEV);
+ }
+ default:
+ driver = get_tty_driver(device, index);
+ if (!driver)
+ return ERR_PTR(-ENODEV);
+ break;
+ }
+ return driver;
+}
+
+/**
+ * tty_kopen - open a tty device for kernel
+ * @device: dev_t of device to open
+ *
+ * Opens tty exclusively for kernel. Performs the driver lookup,
+ * makes sure it's not already opened and performs the first-time
+ * tty initialization.
+ *
+ * Returns the locked initialized &tty_struct
+ *
+ * Claims the global tty_mutex to serialize:
+ * - concurrent first-time tty initialization
+ * - concurrent tty driver removal w/ lookup
+ * - concurrent tty removal from driver table
+ */
+struct tty_struct *tty_kopen(dev_t device)
+{
+ struct tty_struct *tty;
+ struct tty_driver *driver = NULL;
+ int index = -1;
+
+ mutex_lock(&tty_mutex);
+ driver = tty_lookup_driver(device, NULL, &index);
+ if (IS_ERR(driver)) {
+ mutex_unlock(&tty_mutex);
+ return ERR_CAST(driver);
+ }
+
+ /* check whether we're reopening an existing tty */
+ tty = tty_driver_lookup_tty(driver, NULL, index);
+ if (IS_ERR(tty))
+ goto out;
+
+ if (tty) {
+ /* drop kref from tty_driver_lookup_tty() */
+ tty_kref_put(tty);
+ tty = ERR_PTR(-EBUSY);
+ } else { /* tty_init_dev returns tty with the tty_lock held */
+ tty = tty_init_dev(driver, index);
+ if (IS_ERR(tty))
+ goto out;
+ tty_port_set_kopened(tty->port, 1);
+ }
+out:
+ mutex_unlock(&tty_mutex);
+ tty_driver_kref_put(driver);
+ return tty;
+}
+EXPORT_SYMBOL_GPL(tty_kopen);
+
+/**
+ * tty_open_by_driver - open a tty device
+ * @device: dev_t of device to open
+ * @inode: inode of device file
+ * @filp: file pointer to tty
+ *
+ * Performs the driver lookup, checks for a reopen, or otherwise
+ * performs the first-time tty initialization.
+ *
+ * Returns the locked initialized or re-opened &tty_struct
+ *
+ * Claims the global tty_mutex to serialize:
+ * - concurrent first-time tty initialization
+ * - concurrent tty driver removal w/ lookup
+ * - concurrent tty removal from driver table
+ */
+static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
+ struct file *filp)
+{
+ struct tty_struct *tty;
+ struct tty_driver *driver = NULL;
+ int index = -1;
+ int retval;
+
+ mutex_lock(&tty_mutex);
+ driver = tty_lookup_driver(device, filp, &index);
+ if (IS_ERR(driver)) {
+ mutex_unlock(&tty_mutex);
+ return ERR_CAST(driver);
+ }
+
+ /* check whether we're reopening an existing tty */
+ tty = tty_driver_lookup_tty(driver, filp, index);
+ if (IS_ERR(tty)) {
+ mutex_unlock(&tty_mutex);
+ goto out;
+ }
+
+ if (tty) {
+ if (tty_port_kopened(tty->port)) {
+ tty_kref_put(tty);
+ mutex_unlock(&tty_mutex);
+ tty = ERR_PTR(-EBUSY);
+ goto out;
+ }
+ mutex_unlock(&tty_mutex);
+ retval = tty_lock_interruptible(tty);
+ tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
+ if (retval) {
+ if (retval == -EINTR)
+ retval = -ERESTARTSYS;
+ tty = ERR_PTR(retval);
+ goto out;
+ }
+ retval = tty_reopen(tty);
+ if (retval < 0) {
+ tty_unlock(tty);
+ tty = ERR_PTR(retval);
+ }
+ } else { /* Returns with the tty_lock held for now */
+ tty = tty_init_dev(driver, index);
+ mutex_unlock(&tty_mutex);
+ }
+out:
+ tty_driver_kref_put(driver);
+ return tty;
+}
+
+/**
+ * tty_open - open a tty device
+ * @inode: inode of device file
+ * @filp: file pointer to tty
+ *
+ * tty_open and tty_release keep up the tty count that contains the
+ * number of opens done on a tty. We cannot use the inode-count, as
+ * different inodes might point to the same tty.
+ *
+ * Open-counting is needed for pty masters, as well as for keeping
+ * track of serial lines: DTR is dropped when the last close happens.
+ * (This is not done solely through tty->count, now. - Ted 1/27/92)
+ *
+ * The termios state of a pty is reset on first open so that
+ * settings don't persist across reuse.
+ *
+ * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
+ * tty->count should protect the rest.
+ * ->siglock protects ->signal/->sighand
+ *
+ * Note: the tty_unlock/lock cases without a ref are only safe due to
+ * tty_mutex
+ */
+
+static int tty_open(struct inode *inode, struct file *filp)
+{
+ struct tty_struct *tty;
+ int noctty, retval;
+ dev_t device = inode->i_rdev;
+ unsigned saved_flags = filp->f_flags;
+
+ nonseekable_open(inode, filp);
+
+retry_open:
+ retval = tty_alloc_file(filp);
+ if (retval)
+ return -ENOMEM;
+
+ tty = tty_open_current_tty(device, filp);
+ if (!tty)
+ tty = tty_open_by_driver(device, inode, filp);
+
+ if (IS_ERR(tty)) {
+ tty_free_file(filp);
+ retval = PTR_ERR(tty);
+ if (retval != -EAGAIN || signal_pending(current))
+ return retval;
+ schedule();
+ goto retry_open;
+ }
+
+ tty_add_file(tty, filp);
+
+ check_tty_count(tty, __func__);
+ tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
+
+ if (tty->ops->open)
+ retval = tty->ops->open(tty, filp);
+ else
+ retval = -ENODEV;
+ filp->f_flags = saved_flags;
+
+ if (retval) {
+ tty_debug_hangup(tty, "open error %d, releasing\n", retval);
+
+ tty_unlock(tty); /* need to call tty_release without BTM */
+ tty_release(inode, filp);
+ if (retval != -ERESTARTSYS)
+ return retval;
+
+ if (signal_pending(current))
+ return retval;
+
+ schedule();
+ /*
+ * Need to reset f_op in case a hangup happened.
+ */
+ if (tty_hung_up_p(filp))
+ filp->f_op = &tty_fops;
+ goto retry_open;
+ }
+ clear_bit(TTY_HUPPED, &tty->flags);
+
+ noctty = (filp->f_flags & O_NOCTTY) ||
+ (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
+ device == MKDEV(TTYAUX_MAJOR, 1) ||
+ (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
+ tty->driver->subtype == PTY_TYPE_MASTER);
+ if (!noctty)
+ tty_open_proc_set_tty(filp, tty);
+ tty_unlock(tty);
+ return 0;
+}
+
+
+
+/**
+ * tty_poll - check tty status
+ * @filp: file being polled
+ * @wait: poll wait structures to update
+ *
+ * Call the line discipline polling method to obtain the poll
+ * status of the device.
+ *
+ * Locking: locks called line discipline but ldisc poll method
+ * may be re-entered freely by other callers.
+ */
+
+static __poll_t tty_poll(struct file *filp, poll_table *wait)
+{
+ struct tty_struct *tty = file_tty(filp);
+ struct tty_ldisc *ld;
+ __poll_t ret = 0;
+
+ if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
+ return 0;
+
+ ld = tty_ldisc_ref_wait(tty);
+ if (!ld)
+ return hung_up_tty_poll(filp, wait);
+ if (ld->ops->poll)
+ ret = ld->ops->poll(tty, filp, wait);
+ tty_ldisc_deref(ld);
+ return ret;
+}
+
+static int __tty_fasync(int fd, struct file *filp, int on)
+{
+ struct tty_struct *tty = file_tty(filp);
+ unsigned long flags;
+ int retval = 0;
+
+ if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
+ goto out;
+
+ retval = fasync_helper(fd, filp, on, &tty->fasync);
+ if (retval <= 0)
+ goto out;
+
+ if (on) {
+ enum pid_type type;
+ struct pid *pid;
+
+ spin_lock_irqsave(&tty->ctrl_lock, flags);
+ if (tty->pgrp) {
+ pid = tty->pgrp;
+ type = PIDTYPE_PGID;
+ } else {
+ pid = task_pid(current);
+ type = PIDTYPE_TGID;
+ }
+ get_pid(pid);
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+ __f_setown(filp, pid, type, 0);
+ put_pid(pid);
+ retval = 0;
+ }
+out:
+ return retval;
+}
+
+static int tty_fasync(int fd, struct file *filp, int on)
+{
+ struct tty_struct *tty = file_tty(filp);
+ int retval = -ENOTTY;
+
+ tty_lock(tty);
+ if (!tty_hung_up_p(filp))
+ retval = __tty_fasync(fd, filp, on);
+ tty_unlock(tty);
+
+ return retval;
+}
+
+/**
+ * tiocsti - fake input character
+ * @tty: tty to fake input into
+ * @p: pointer to character
+ *
+ * Fake input to a tty device. Does the necessary locking and
+ * input management.
+ *
+ * FIXME: does not honour flow control ??
+ *
+ * Locking:
+ * Called functions take tty_ldiscs_lock
+ * current->signal->tty check is safe without locks
+ *
+ * FIXME: may race normal receive processing
+ */
+
+static int tiocsti(struct tty_struct *tty, char __user *p)
+{
+ char ch, mbz = 0;
+ struct tty_ldisc *ld;
+
+ if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (get_user(ch, p))
+ return -EFAULT;
+ tty_audit_tiocsti(tty, ch);
+ ld = tty_ldisc_ref_wait(tty);
+ if (!ld)
+ return -EIO;
+ ld->ops->receive_buf(tty, &ch, &mbz, 1);
+ tty_ldisc_deref(ld);
+ return 0;
+}
+
+/**
+ * tiocgwinsz - implement window query ioctl
+ * @tty; tty
+ * @arg: user buffer for result
+ *
+ * Copies the kernel idea of the window size into the user buffer.
+ *
+ * Locking: tty->winsize_mutex is taken to ensure the winsize data
+ * is consistent.
+ */
+
+static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
+{
+ int err;
+
+ mutex_lock(&tty->winsize_mutex);
+ err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
+ mutex_unlock(&tty->winsize_mutex);
+
+ return err ? -EFAULT: 0;
+}
+
+/**
+ * tty_do_resize - resize event
+ * @tty: tty being resized
+ * @rows: rows (character)
+ * @cols: cols (character)
+ *
+ * Update the termios variables and send the necessary signals to
+ * peform a terminal resize correctly
+ */
+
+int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
+{
+ struct pid *pgrp;
+
+ /* Lock the tty */
+ mutex_lock(&tty->winsize_mutex);
+ if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
+ goto done;
+
+ /* Signal the foreground process group */
+ pgrp = tty_get_pgrp(tty);
+ if (pgrp)
+ kill_pgrp(pgrp, SIGWINCH, 1);
+ put_pid(pgrp);
+
+ tty->winsize = *ws;
+done:
+ mutex_unlock(&tty->winsize_mutex);
+ return 0;
+}
+EXPORT_SYMBOL(tty_do_resize);
+
+/**
+ * tiocswinsz - implement window size set ioctl
+ * @tty; tty side of tty
+ * @arg: user buffer for result
+ *
+ * Copies the user idea of the window size to the kernel. Traditionally
+ * this is just advisory information but for the Linux console it
+ * actually has driver level meaning and triggers a VC resize.
+ *
+ * Locking:
+ * Driver dependent. The default do_resize method takes the
+ * tty termios mutex and ctrl_lock. The console takes its own lock
+ * then calls into the default method.
+ */
+
+static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
+{
+ struct winsize tmp_ws;
+ if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
+ return -EFAULT;
+
+ if (tty->ops->resize)
+ return tty->ops->resize(tty, &tmp_ws);
+ else
+ return tty_do_resize(tty, &tmp_ws);
+}
+
+/**
+ * tioccons - allow admin to move logical console
+ * @file: the file to become console
+ *
+ * Allow the administrator to move the redirected console device
+ *
+ * Locking: uses redirect_lock to guard the redirect information
+ */
+
+static int tioccons(struct file *file)
+{
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (file->f_op->write == redirected_tty_write) {
+ struct file *f;
+ spin_lock(&redirect_lock);
+ f = redirect;
+ redirect = NULL;
+ spin_unlock(&redirect_lock);
+ if (f)
+ fput(f);
+ return 0;
+ }
+ spin_lock(&redirect_lock);
+ if (redirect) {
+ spin_unlock(&redirect_lock);
+ return -EBUSY;
+ }
+ redirect = get_file(file);
+ spin_unlock(&redirect_lock);
+ return 0;
+}
+
+/**
+ * fionbio - non blocking ioctl
+ * @file: file to set blocking value
+ * @p: user parameter
+ *
+ * Historical tty interfaces had a blocking control ioctl before
+ * the generic functionality existed. This piece of history is preserved
+ * in the expected tty API of posix OS's.
+ *
+ * Locking: none, the open file handle ensures it won't go away.
+ */
+
+static int fionbio(struct file *file, int __user *p)
+{
+ int nonblock;
+
+ if (get_user(nonblock, p))
+ return -EFAULT;
+
+ spin_lock(&file->f_lock);
+ if (nonblock)
+ file->f_flags |= O_NONBLOCK;
+ else
+ file->f_flags &= ~O_NONBLOCK;
+ spin_unlock(&file->f_lock);
+ return 0;
+}
+
+/**
+ * tiocsetd - set line discipline
+ * @tty: tty device
+ * @p: pointer to user data
+ *
+ * Set the line discipline according to user request.
+ *
+ * Locking: see tty_set_ldisc, this function is just a helper
+ */
+
+static int tiocsetd(struct tty_struct *tty, int __user *p)
+{
+ int disc;
+ int ret;
+
+ if (get_user(disc, p))
+ return -EFAULT;
+
+ ret = tty_set_ldisc(tty, disc);
+
+ return ret;
+}
+
+/**
+ * tiocgetd - get line discipline
+ * @tty: tty device
+ * @p: pointer to user data
+ *
+ * Retrieves the line discipline id directly from the ldisc.
+ *
+ * Locking: waits for ldisc reference (in case the line discipline
+ * is changing or the tty is being hungup)
+ */
+
+static int tiocgetd(struct tty_struct *tty, int __user *p)
+{
+ struct tty_ldisc *ld;
+ int ret;
+
+ ld = tty_ldisc_ref_wait(tty);
+ if (!ld)
+ return -EIO;
+ ret = put_user(ld->ops->num, p);
+ tty_ldisc_deref(ld);
+ return ret;
+}
+
+/**
+ * send_break - performed time break
+ * @tty: device to break on
+ * @duration: timeout in mS
+ *
+ * Perform a timed break on hardware that lacks its own driver level
+ * timed break functionality.
+ *
+ * Locking:
+ * atomic_write_lock serializes
+ *
+ */
+
+static int send_break(struct tty_struct *tty, unsigned int duration)
+{
+ int retval;
+
+ if (tty->ops->break_ctl == NULL)
+ return 0;
+
+ if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
+ retval = tty->ops->break_ctl(tty, duration);
+ else {
+ /* Do the work ourselves */
+ if (tty_write_lock(tty, 0) < 0)
+ return -EINTR;
+ retval = tty->ops->break_ctl(tty, -1);
+ if (retval)
+ goto out;
+ if (!signal_pending(current))
+ msleep_interruptible(duration);
+ retval = tty->ops->break_ctl(tty, 0);
+out:
+ tty_write_unlock(tty);
+ if (signal_pending(current))
+ retval = -EINTR;
+ }
+ return retval;
+}
+
+/**
+ * tty_tiocmget - get modem status
+ * @tty: tty device
+ * @file: user file pointer
+ * @p: pointer to result
+ *
+ * Obtain the modem status bits from the tty driver if the feature
+ * is supported. Return -EINVAL if it is not available.
+ *
+ * Locking: none (up to the driver)
+ */
+
+static int tty_tiocmget(struct tty_struct *tty, int __user *p)
+{
+ int retval = -EINVAL;
+
+ if (tty->ops->tiocmget) {
+ retval = tty->ops->tiocmget(tty);
+
+ if (retval >= 0)
+ retval = put_user(retval, p);
+ }
+ return retval;
+}
+
+/**
+ * tty_tiocmset - set modem status
+ * @tty: tty device
+ * @cmd: command - clear bits, set bits or set all
+ * @p: pointer to desired bits
+ *
+ * Set the modem status bits from the tty driver if the feature
+ * is supported. Return -EINVAL if it is not available.
+ *
+ * Locking: none (up to the driver)
+ */
+
+static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
+ unsigned __user *p)
+{
+ int retval;
+ unsigned int set, clear, val;
+
+ if (tty->ops->tiocmset == NULL)
+ return -EINVAL;
+
+ retval = get_user(val, p);
+ if (retval)
+ return retval;
+ set = clear = 0;
+ switch (cmd) {
+ case TIOCMBIS:
+ set = val;
+ break;
+ case TIOCMBIC:
+ clear = val;
+ break;
+ case TIOCMSET:
+ set = val;
+ clear = ~val;
+ break;
+ }
+ set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
+ clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
+ return tty->ops->tiocmset(tty, set, clear);
+}
+
+static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
+{
+ int retval = -EINVAL;
+ struct serial_icounter_struct icount;
+ memset(&icount, 0, sizeof(icount));
+ if (tty->ops->get_icount)
+ retval = tty->ops->get_icount(tty, &icount);
+ if (retval != 0)
+ return retval;
+ if (copy_to_user(arg, &icount, sizeof(icount)))
+ return -EFAULT;
+ return 0;
+}
+
+static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
+{
+ static DEFINE_RATELIMIT_STATE(depr_flags,
+ DEFAULT_RATELIMIT_INTERVAL,
+ DEFAULT_RATELIMIT_BURST);
+ char comm[TASK_COMM_LEN];
+ int flags;
+
+ if (get_user(flags, &ss->flags))
+ return;
+
+ flags &= ASYNC_DEPRECATED;
+
+ if (flags && __ratelimit(&depr_flags))
+ pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
+ __func__, get_task_comm(comm, current), flags);
+}
+
+/*
+ * if pty, return the slave side (real_tty)
+ * otherwise, return self
+ */
+static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
+{
+ if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
+ tty->driver->subtype == PTY_TYPE_MASTER)
+ tty = tty->link;
+ return tty;
+}
+
+/*
+ * Split this up, as gcc can choke on it otherwise..
+ */
+long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct tty_struct *tty = file_tty(file);
+ struct tty_struct *real_tty;
+ void __user *p = (void __user *)arg;
+ int retval;
+ struct tty_ldisc *ld;
+
+ if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
+ return -EINVAL;
+
+ real_tty = tty_pair_get_tty(tty);
+
+ /*
+ * Factor out some common prep work
+ */
+ switch (cmd) {
+ case TIOCSETD:
+ case TIOCSBRK:
+ case TIOCCBRK:
+ case TCSBRK:
+ case TCSBRKP:
+ retval = tty_check_change(tty);
+ if (retval)
+ return retval;
+ if (cmd != TIOCCBRK) {
+ tty_wait_until_sent(tty, 0);
+ if (signal_pending(current))
+ return -EINTR;
+ }
+ break;
+ }
+
+ /*
+ * Now do the stuff.
+ */
+ switch (cmd) {
+ case TIOCSTI:
+ return tiocsti(tty, p);
+ case TIOCGWINSZ:
+ return tiocgwinsz(real_tty, p);
+ case TIOCSWINSZ:
+ return tiocswinsz(real_tty, p);
+ case TIOCCONS:
+ return real_tty != tty ? -EINVAL : tioccons(file);
+ case FIONBIO:
+ return fionbio(file, p);
+ case TIOCEXCL:
+ set_bit(TTY_EXCLUSIVE, &tty->flags);
+ return 0;
+ case TIOCNXCL:
+ clear_bit(TTY_EXCLUSIVE, &tty->flags);
+ return 0;
+ case TIOCGEXCL:
+ {
+ int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
+ return put_user(excl, (int __user *)p);
+ }
+ case TIOCGETD:
+ return tiocgetd(tty, p);
+ case TIOCSETD:
+ return tiocsetd(tty, p);
+ case TIOCVHANGUP:
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ tty_vhangup(tty);
+ return 0;
+ case TIOCGDEV:
+ {
+ unsigned int ret = new_encode_dev(tty_devnum(real_tty));
+ return put_user(ret, (unsigned int __user *)p);
+ }
+ /*
+ * Break handling
+ */
+ case TIOCSBRK: /* Turn break on, unconditionally */
+ if (tty->ops->break_ctl)
+ return tty->ops->break_ctl(tty, -1);
+ return 0;
+ case TIOCCBRK: /* Turn break off, unconditionally */
+ if (tty->ops->break_ctl)
+ return tty->ops->break_ctl(tty, 0);
+ return 0;
+ case TCSBRK: /* SVID version: non-zero arg --> no break */
+ /* non-zero arg means wait for all output data
+ * to be sent (performed above) but don't send break.
+ * This is used by the tcdrain() termios function.
+ */
+ if (!arg)
+ return send_break(tty, 250);
+ return 0;
+ case TCSBRKP: /* support for POSIX tcsendbreak() */
+ return send_break(tty, arg ? arg*100 : 250);
+
+ case TIOCMGET:
+ return tty_tiocmget(tty, p);
+ case TIOCMSET:
+ case TIOCMBIC:
+ case TIOCMBIS:
+ return tty_tiocmset(tty, cmd, p);
+ case TIOCGICOUNT:
+ retval = tty_tiocgicount(tty, p);
+ /* For the moment allow fall through to the old method */
+ if (retval != -EINVAL)
+ return retval;
+ break;
+ case TCFLSH:
+ switch (arg) {
+ case TCIFLUSH:
+ case TCIOFLUSH:
+ /* flush tty buffer and allow ldisc to process ioctl */
+ tty_buffer_flush(tty, NULL);
+ break;
+ }
+ break;
+ case TIOCSSERIAL:
+ tty_warn_deprecated_flags(p);
+ break;
+ case TIOCGPTPEER:
+ /* Special because the struct file is needed */
+ return ptm_open_peer(file, tty, (int)arg);
+ default:
+ retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
+ if (retval != -ENOIOCTLCMD)
+ return retval;
+ }
+ if (tty->ops->ioctl) {
+ retval = tty->ops->ioctl(tty, cmd, arg);
+ if (retval != -ENOIOCTLCMD)
+ return retval;
+ }
+ ld = tty_ldisc_ref_wait(tty);
+ if (!ld)
+ return hung_up_tty_ioctl(file, cmd, arg);
+ retval = -EINVAL;
+ if (ld->ops->ioctl) {
+ retval = ld->ops->ioctl(tty, file, cmd, arg);
+ if (retval == -ENOIOCTLCMD)
+ retval = -ENOTTY;
+ }
+ tty_ldisc_deref(ld);
+ return retval;
+}
+
+#ifdef CONFIG_COMPAT
+static long tty_compat_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct tty_struct *tty = file_tty(file);
+ struct tty_ldisc *ld;
+ int retval = -ENOIOCTLCMD;
+
+ if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
+ return -EINVAL;
+
+ if (tty->ops->compat_ioctl) {
+ retval = tty->ops->compat_ioctl(tty, cmd, arg);
+ if (retval != -ENOIOCTLCMD)
+ return retval;
+ }
+
+ ld = tty_ldisc_ref_wait(tty);
+ if (!ld)
+ return hung_up_tty_compat_ioctl(file, cmd, arg);
+ if (ld->ops->compat_ioctl)
+ retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
+ else
+ retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
+ tty_ldisc_deref(ld);
+
+ return retval;
+}
+#endif
+
+static int this_tty(const void *t, struct file *file, unsigned fd)
+{
+ if (likely(file->f_op->read != tty_read))
+ return 0;
+ return file_tty(file) != t ? 0 : fd + 1;
+}
+
+/*
+ * This implements the "Secure Attention Key" --- the idea is to
+ * prevent trojan horses by killing all processes associated with this
+ * tty when the user hits the "Secure Attention Key". Required for
+ * super-paranoid applications --- see the Orange Book for more details.
+ *
+ * This code could be nicer; ideally it should send a HUP, wait a few
+ * seconds, then send a INT, and then a KILL signal. But you then
+ * have to coordinate with the init process, since all processes associated
+ * with the current tty must be dead before the new getty is allowed
+ * to spawn.
+ *
+ * Now, if it would be correct ;-/ The current code has a nasty hole -
+ * it doesn't catch files in flight. We may send the descriptor to ourselves
+ * via AF_UNIX socket, close it and later fetch from socket. FIXME.
+ *
+ * Nasty bug: do_SAK is being called in interrupt context. This can
+ * deadlock. We punt it up to process context. AKPM - 16Mar2001
+ */
+void __do_SAK(struct tty_struct *tty)
+{
+#ifdef TTY_SOFT_SAK
+ tty_hangup(tty);
+#else
+ struct task_struct *g, *p;
+ struct pid *session;
+ int i;
+
+ if (!tty)
+ return;
+ session = tty->session;
+
+ tty_ldisc_flush(tty);
+
+ tty_driver_flush_buffer(tty);
+
+ read_lock(&tasklist_lock);
+ /* Kill the entire session */
+ do_each_pid_task(session, PIDTYPE_SID, p) {
+ tty_notice(tty, "SAK: killed process %d (%s): by session\n",
+ task_pid_nr(p), p->comm);
+ send_sig(SIGKILL, p, 1);
+ } while_each_pid_task(session, PIDTYPE_SID, p);
+
+ /* Now kill any processes that happen to have the tty open */
+ do_each_thread(g, p) {
+ if (p->signal->tty == tty) {
+ tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
+ task_pid_nr(p), p->comm);
+ send_sig(SIGKILL, p, 1);
+ continue;
+ }
+ task_lock(p);
+ i = iterate_fd(p->files, 0, this_tty, tty);
+ if (i != 0) {
+ tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
+ task_pid_nr(p), p->comm, i - 1);
+ force_sig(SIGKILL, p);
+ }
+ task_unlock(p);
+ } while_each_thread(g, p);
+ read_unlock(&tasklist_lock);
+#endif
+}
+
+static void do_SAK_work(struct work_struct *work)
+{
+ struct tty_struct *tty =
+ container_of(work, struct tty_struct, SAK_work);
+ __do_SAK(tty);
+}
+
+/*
+ * The tq handling here is a little racy - tty->SAK_work may already be queued.
+ * Fortunately we don't need to worry, because if ->SAK_work is already queued,
+ * the values which we write to it will be identical to the values which it
+ * already has. --akpm
+ */
+void do_SAK(struct tty_struct *tty)
+{
+ if (!tty)
+ return;
+ schedule_work(&tty->SAK_work);
+}
+
+EXPORT_SYMBOL(do_SAK);
+
+static int dev_match_devt(struct device *dev, const void *data)
+{
+ const dev_t *devt = data;
+ return dev->devt == *devt;
+}
+
+/* Must put_device() after it's unused! */
+static struct device *tty_get_device(struct tty_struct *tty)
+{
+ dev_t devt = tty_devnum(tty);
+ return class_find_device(tty_class, NULL, &devt, dev_match_devt);
+}
+
+
+/**
+ * alloc_tty_struct
+ *
+ * This subroutine allocates and initializes a tty structure.
+ *
+ * Locking: none - tty in question is not exposed at this point
+ */
+
+struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
+{
+ struct tty_struct *tty;
+
+ tty = kzalloc(sizeof(*tty), GFP_KERNEL);
+ if (!tty)
+ return NULL;
+
+ kref_init(&tty->kref);
+ tty->magic = TTY_MAGIC;
+ if (tty_ldisc_init(tty)) {
+ kfree(tty);
+ return NULL;
+ }
+ tty->session = NULL;
+ tty->pgrp = NULL;
+ mutex_init(&tty->legacy_mutex);
+ mutex_init(&tty->throttle_mutex);
+ init_rwsem(&tty->termios_rwsem);
+ mutex_init(&tty->winsize_mutex);
+ init_ldsem(&tty->ldisc_sem);
+ init_waitqueue_head(&tty->write_wait);
+ init_waitqueue_head(&tty->read_wait);
+ INIT_WORK(&tty->hangup_work, do_tty_hangup);
+ mutex_init(&tty->atomic_write_lock);
+ spin_lock_init(&tty->ctrl_lock);
+ spin_lock_init(&tty->flow_lock);
+ spin_lock_init(&tty->files_lock);
+ INIT_LIST_HEAD(&tty->tty_files);
+ INIT_WORK(&tty->SAK_work, do_SAK_work);
+
+ tty->driver = driver;
+ tty->ops = driver->ops;
+ tty->index = idx;
+ tty_line_name(driver, idx, tty->name);
+ tty->dev = tty_get_device(tty);
+
+ return tty;
+}
+
+/**
+ * tty_put_char - write one character to a tty
+ * @tty: tty
+ * @ch: character
+ *
+ * Write one byte to the tty using the provided put_char method
+ * if present. Returns the number of characters successfully output.
+ *
+ * Note: the specific put_char operation in the driver layer may go
+ * away soon. Don't call it directly, use this method
+ */
+
+int tty_put_char(struct tty_struct *tty, unsigned char ch)
+{
+ if (tty->ops->put_char)
+ return tty->ops->put_char(tty, ch);
+ return tty->ops->write(tty, &ch, 1);
+}
+EXPORT_SYMBOL_GPL(tty_put_char);
+
+struct class *tty_class;
+
+static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
+ unsigned int index, unsigned int count)
+{
+ int err;
+
+ /* init here, since reused cdevs cause crashes */
+ driver->cdevs[index] = cdev_alloc();
+ if (!driver->cdevs[index])
+ return -ENOMEM;
+ driver->cdevs[index]->ops = &tty_fops;
+ driver->cdevs[index]->owner = driver->owner;
+ err = cdev_add(driver->cdevs[index], dev, count);
+ if (err)
+ kobject_put(&driver->cdevs[index]->kobj);
+ return err;
+}
+
+/**
+ * tty_register_device - register a tty device
+ * @driver: the tty driver that describes the tty device
+ * @index: the index in the tty driver for this tty device
+ * @device: a struct device that is associated with this tty device.
+ * This field is optional, if there is no known struct device
+ * for this tty device it can be set to NULL safely.
+ *
+ * Returns a pointer to the struct device for this tty device
+ * (or ERR_PTR(-EFOO) on error).
+ *
+ * This call is required to be made to register an individual tty device
+ * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
+ * that bit is not set, this function should not be called by a tty
+ * driver.
+ *
+ * Locking: ??
+ */
+
+struct device *tty_register_device(struct tty_driver *driver, unsigned index,
+ struct device *device)
+{
+ return tty_register_device_attr(driver, index, device, NULL, NULL);
+}
+EXPORT_SYMBOL(tty_register_device);
+
+static void tty_device_create_release(struct device *dev)
+{
+ dev_dbg(dev, "releasing...\n");
+ kfree(dev);
+}
+
+/**
+ * tty_register_device_attr - register a tty device
+ * @driver: the tty driver that describes the tty device
+ * @index: the index in the tty driver for this tty device
+ * @device: a struct device that is associated with this tty device.
+ * This field is optional, if there is no known struct device
+ * for this tty device it can be set to NULL safely.
+ * @drvdata: Driver data to be set to device.
+ * @attr_grp: Attribute group to be set on device.
+ *
+ * Returns a pointer to the struct device for this tty device
+ * (or ERR_PTR(-EFOO) on error).
+ *
+ * This call is required to be made to register an individual tty device
+ * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
+ * that bit is not set, this function should not be called by a tty
+ * driver.
+ *
+ * Locking: ??
+ */
+struct device *tty_register_device_attr(struct tty_driver *driver,
+ unsigned index, struct device *device,
+ void *drvdata,
+ const struct attribute_group **attr_grp)
+{
+ char name[64];
+ dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
+ struct ktermios *tp;
+ struct device *dev;
+ int retval;
+
+ if (index >= driver->num) {
+ pr_err("%s: Attempt to register invalid tty line number (%d)\n",
+ driver->name, index);
+ return ERR_PTR(-EINVAL);
+ }
+
+ if (driver->type == TTY_DRIVER_TYPE_PTY)
+ pty_line_name(driver, index, name);
+ else
+ tty_line_name(driver, index, name);
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev)
+ return ERR_PTR(-ENOMEM);
+
+ dev->devt = devt;
+ dev->class = tty_class;
+ dev->parent = device;
+ dev->release = tty_device_create_release;
+ dev_set_name(dev, "%s", name);
+ dev->groups = attr_grp;
+ dev_set_drvdata(dev, drvdata);
+
+ dev_set_uevent_suppress(dev, 1);
+
+ retval = device_register(dev);
+ if (retval)
+ goto err_put;
+
+ if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
+ /*
+ * Free any saved termios data so that the termios state is
+ * reset when reusing a minor number.
+ */
+ tp = driver->termios[index];
+ if (tp) {
+ driver->termios[index] = NULL;
+ kfree(tp);
+ }
+
+ retval = tty_cdev_add(driver, devt, index, 1);
+ if (retval)
+ goto err_del;
+ }
+
+ dev_set_uevent_suppress(dev, 0);
+ kobject_uevent(&dev->kobj, KOBJ_ADD);
+
+ return dev;
+
+err_del:
+ device_del(dev);
+err_put:
+ put_device(dev);
+
+ return ERR_PTR(retval);
+}
+EXPORT_SYMBOL_GPL(tty_register_device_attr);
+
+/**
+ * tty_unregister_device - unregister a tty device
+ * @driver: the tty driver that describes the tty device
+ * @index: the index in the tty driver for this tty device
+ *
+ * If a tty device is registered with a call to tty_register_device() then
+ * this function must be called when the tty device is gone.
+ *
+ * Locking: ??
+ */
+
+void tty_unregister_device(struct tty_driver *driver, unsigned index)
+{
+ device_destroy(tty_class,
+ MKDEV(driver->major, driver->minor_start) + index);
+ if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
+ cdev_del(driver->cdevs[index]);
+ driver->cdevs[index] = NULL;
+ }
+}
+EXPORT_SYMBOL(tty_unregister_device);
+
+/**
+ * __tty_alloc_driver -- allocate tty driver
+ * @lines: count of lines this driver can handle at most
+ * @owner: module which is responsible for this driver
+ * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
+ *
+ * This should not be called directly, some of the provided macros should be
+ * used instead. Use IS_ERR and friends on @retval.
+ */
+struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
+ unsigned long flags)
+{
+ struct tty_driver *driver;
+ unsigned int cdevs = 1;
+ int err;
+
+ if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
+ return ERR_PTR(-EINVAL);
+
+ driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
+ if (!driver)
+ return ERR_PTR(-ENOMEM);
+
+ kref_init(&driver->kref);
+ driver->magic = TTY_DRIVER_MAGIC;
+ driver->num = lines;
+ driver->owner = owner;
+ driver->flags = flags;
+
+ if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
+ driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
+ GFP_KERNEL);
+ driver->termios = kcalloc(lines, sizeof(*driver->termios),
+ GFP_KERNEL);
+ if (!driver->ttys || !driver->termios) {
+ err = -ENOMEM;
+ goto err_free_all;
+ }
+ }
+
+ if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
+ driver->ports = kcalloc(lines, sizeof(*driver->ports),
+ GFP_KERNEL);
+ if (!driver->ports) {
+ err = -ENOMEM;
+ goto err_free_all;
+ }
+ cdevs = lines;
+ }
+
+ driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
+ if (!driver->cdevs) {
+ err = -ENOMEM;
+ goto err_free_all;
+ }
+
+ return driver;
+err_free_all:
+ kfree(driver->ports);
+ kfree(driver->ttys);
+ kfree(driver->termios);
+ kfree(driver->cdevs);
+ kfree(driver);
+ return ERR_PTR(err);
+}
+EXPORT_SYMBOL(__tty_alloc_driver);
+
+static void destruct_tty_driver(struct kref *kref)
+{
+ struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
+ int i;
+ struct ktermios *tp;
+
+ if (driver->flags & TTY_DRIVER_INSTALLED) {
+ for (i = 0; i < driver->num; i++) {
+ tp = driver->termios[i];
+ if (tp) {
+ driver->termios[i] = NULL;
+ kfree(tp);
+ }
+ if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
+ tty_unregister_device(driver, i);
+ }
+ proc_tty_unregister_driver(driver);
+ if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
+ cdev_del(driver->cdevs[0]);
+ }
+ kfree(driver->cdevs);
+ kfree(driver->ports);
+ kfree(driver->termios);
+ kfree(driver->ttys);
+ kfree(driver);
+}
+
+void tty_driver_kref_put(struct tty_driver *driver)
+{
+ kref_put(&driver->kref, destruct_tty_driver);
+}
+EXPORT_SYMBOL(tty_driver_kref_put);
+
+void tty_set_operations(struct tty_driver *driver,
+ const struct tty_operations *op)
+{
+ driver->ops = op;
+};
+EXPORT_SYMBOL(tty_set_operations);
+
+void put_tty_driver(struct tty_driver *d)
+{
+ tty_driver_kref_put(d);
+}
+EXPORT_SYMBOL(put_tty_driver);
+
+/*
+ * Called by a tty driver to register itself.
+ */
+int tty_register_driver(struct tty_driver *driver)
+{
+ int error;
+ int i;
+ dev_t dev;
+ struct device *d;
+
+ if (!driver->major) {
+ error = alloc_chrdev_region(&dev, driver->minor_start,
+ driver->num, driver->name);
+ if (!error) {
+ driver->major = MAJOR(dev);
+ driver->minor_start = MINOR(dev);
+ }
+ } else {
+ dev = MKDEV(driver->major, driver->minor_start);
+ error = register_chrdev_region(dev, driver->num, driver->name);
+ }
+ if (error < 0)
+ goto err;
+
+ if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
+ error = tty_cdev_add(driver, dev, 0, driver->num);
+ if (error)
+ goto err_unreg_char;
+ }
+
+ mutex_lock(&tty_mutex);
+ list_add(&driver->tty_drivers, &tty_drivers);
+ mutex_unlock(&tty_mutex);
+
+ if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
+ for (i = 0; i < driver->num; i++) {
+ d = tty_register_device(driver, i, NULL);
+ if (IS_ERR(d)) {
+ error = PTR_ERR(d);
+ goto err_unreg_devs;
+ }
+ }
+ }
+ proc_tty_register_driver(driver);
+ driver->flags |= TTY_DRIVER_INSTALLED;
+ return 0;
+
+err_unreg_devs:
+ for (i--; i >= 0; i--)
+ tty_unregister_device(driver, i);
+
+ mutex_lock(&tty_mutex);
+ list_del(&driver->tty_drivers);
+ mutex_unlock(&tty_mutex);
+
+err_unreg_char:
+ unregister_chrdev_region(dev, driver->num);
+err:
+ return error;
+}
+EXPORT_SYMBOL(tty_register_driver);
+
+/*
+ * Called by a tty driver to unregister itself.
+ */
+int tty_unregister_driver(struct tty_driver *driver)
+{
+#if 0
+ /* FIXME */
+ if (driver->refcount)
+ return -EBUSY;
+#endif
+ unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
+ driver->num);
+ mutex_lock(&tty_mutex);
+ list_del(&driver->tty_drivers);
+ mutex_unlock(&tty_mutex);
+ return 0;
+}
+
+EXPORT_SYMBOL(tty_unregister_driver);
+
+dev_t tty_devnum(struct tty_struct *tty)
+{
+ return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
+}
+EXPORT_SYMBOL(tty_devnum);
+
+void tty_default_fops(struct file_operations *fops)
+{
+ *fops = tty_fops;
+}
+
+static char *tty_devnode(struct device *dev, umode_t *mode)
+{
+ if (!mode)
+ return NULL;
+ if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
+ dev->devt == MKDEV(TTYAUX_MAJOR, 2))
+ *mode = 0666;
+ return NULL;
+}
+
+static int __init tty_class_init(void)
+{
+ tty_class = class_create(THIS_MODULE, "tty");
+ if (IS_ERR(tty_class))
+ return PTR_ERR(tty_class);
+ tty_class->devnode = tty_devnode;
+ return 0;
+}
+
+postcore_initcall(tty_class_init);
+
+/* 3/2004 jmc: why do these devices exist? */
+static struct cdev tty_cdev, console_cdev;
+
+static ssize_t show_cons_active(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct console *cs[16];
+ int i = 0;
+ struct console *c;
+ ssize_t count = 0;
+
+ console_lock();
+ for_each_console(c) {
+ if (!c->device)
+ continue;
+ if (!c->write)
+ continue;
+ if ((c->flags & CON_ENABLED) == 0)
+ continue;
+ cs[i++] = c;
+ if (i >= ARRAY_SIZE(cs))
+ break;
+ }
+ while (i--) {
+ int index = cs[i]->index;
+ struct tty_driver *drv = cs[i]->device(cs[i], &index);
+
+ /* don't resolve tty0 as some programs depend on it */
+ if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
+ count += tty_line_name(drv, index, buf + count);
+ else
+ count += sprintf(buf + count, "%s%d",
+ cs[i]->name, cs[i]->index);
+
+ count += sprintf(buf + count, "%c", i ? ' ':'\n');
+ }
+ console_unlock();
+
+ return count;
+}
+static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
+
+static struct attribute *cons_dev_attrs[] = {
+ &dev_attr_active.attr,
+ NULL
+};
+
+ATTRIBUTE_GROUPS(cons_dev);
+
+static struct device *consdev;
+
+void console_sysfs_notify(void)
+{
+ if (consdev)
+ sysfs_notify(&consdev->kobj, NULL, "active");
+}
+
+/*
+ * Ok, now we can initialize the rest of the tty devices and can count
+ * on memory allocations, interrupts etc..
+ */
+int __init tty_init(void)
+{
+ cdev_init(&tty_cdev, &tty_fops);
+ if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
+ register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
+ panic("Couldn't register /dev/tty driver\n");
+ device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
+
+ cdev_init(&console_cdev, &console_fops);
+ if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
+ register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
+ panic("Couldn't register /dev/console driver\n");
+ consdev = device_create_with_groups(tty_class, NULL,
+ MKDEV(TTYAUX_MAJOR, 1), NULL,
+ cons_dev_groups, "console");
+ if (IS_ERR(consdev))
+ consdev = NULL;
+
+#ifdef CONFIG_VT
+ vty_init(&console_fops);
+#endif
+ return 0;
+}
+