tty: remove resize window special case

This moves it to being a tty operation. That removes special cases and now
also means that resize can be picked up by um and other non vt consoles
which may have a resize operation.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

6 files changed, 121 insertions, 54 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 0e6866fe0f96..a27160ba21d7 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2496,45 +2496,25 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
 }
 
 /**
- *      tiocswinsz              -       implement window size set ioctl
- *      @tty; tty
- *      @arg: user buffer for result
+ *      tty_do_resize           -       resize event
+ *      @tty: tty being resized
+ *      @real_tty: real tty (if using a pty/tty pair)
+ *      @rows: rows (character)
+ *      @cols: cols (character)
  *
- *      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:
- *              Called function use the console_sem is used to ensure we do
- *      not try and resize the console twice at once.
- *              The tty->termios_mutex is used to ensure we don't double
- *      resize and get confused. Lock order - tty->termios_mutex before
- *      console sem
+ *      Update the termios variables and send the neccessary signals to
+ *      peform a terminal resize correctly
  */
 
-static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
-        struct winsize __user *arg)
+int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
+                                        struct winsize *ws)
 {
-        struct winsize tmp_ws;
         struct pid *pgrp, *rpgrp;
         unsigned long flags;
 
-        if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
-                return -EFAULT;
-
         mutex_lock(&tty->termios_mutex);
-        if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg)))
+        if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
                 goto done;
-
-#ifdef CONFIG_VT
-        if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
-                if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col,
-                                        tmp_ws.ws_row)) {
-                        mutex_unlock(&tty->termios_mutex);
-                        return -ENXIO;
-                }
-        }
-#endif
         /* Get the PID values and reference them so we can
            avoid holding the tty ctrl lock while sending signals */
         spin_lock_irqsave(&tty->ctrl_lock, flags);
@@ -2550,14 +2530,42 @@ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
         put_pid(pgrp);
         put_pid(rpgrp);
 
-        tty->winsize = tmp_ws;
-        real_tty->winsize = tmp_ws;
+        tty->winsize = *ws;
+        real_tty->winsize = *ws;
 done:
         mutex_unlock(&tty->termios_mutex);
         return 0;
 }
 
 /**
+ *      tiocswinsz              -       implement window size set ioctl
+ *      @tty; 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 dependant. 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 tty_struct *real_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, real_tty, &tmp_ws);
+        else
+                return tty_do_resize(tty, real_tty, &tmp_ws);
+}
+
+/**
  *      tioccons        -       allow admin to move logical console
  *      @file: the file to become console
  *
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 1bc00c9d860d..60359c360912 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -803,7 +803,25 @@ static inline int resize_screen(struct vc_data *vc, int width, int height,
  */
 #define VC_RESIZE_MAXCOL (32767)
 #define VC_RESIZE_MAXROW (32767)
-int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
+
+/**
+ *      vc_do_resize    -       resizing method for the tty
+ *      @tty: tty being resized
+ *      @real_tty: real tty (different to tty if a pty/tty pair)
+ *      @vc: virtual console private data
+ *      @cols: columns
+ *      @lines: lines
+ *
+ *      Resize a virtual console, clipping according to the actual constraints.
+ *      If the caller passes a tty structure then update the termios winsize
+ *      information and perform any neccessary signal handling.
+ *
+ *      Caller must hold the console semaphore. Takes the termios mutex and
+ *      ctrl_lock of the tty IFF a tty is passed.
+ */
+
+static int vc_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
+                struct vc_data *vc, unsigned int cols, unsigned int lines)
 {
         unsigned long old_origin, new_origin, new_scr_end, rlth, rrem, err = 0;
         unsigned int old_cols, old_rows, old_row_size, old_screen_size;
@@ -907,24 +925,15 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
         gotoxy(vc, vc->vc_x, vc->vc_y);
         save_cur(vc);
 
-        if (vc->vc_tty) {
-                struct winsize ws, *cws = &vc->vc_tty->winsize;
-                struct pid *pgrp = NULL;
-
+        if (tty) {
+                /* Rewrite the requested winsize data with the actual
+                   resulting sizes */
+                struct winsize ws;
                 memset(&ws, 0, sizeof(ws));
                 ws.ws_row = vc->vc_rows;
                 ws.ws_col = vc->vc_cols;
                 ws.ws_ypixel = vc->vc_scan_lines;
-
-                spin_lock_irq(&vc->vc_tty->ctrl_lock);
-                if ((ws.ws_row != cws->ws_row || ws.ws_col != cws->ws_col))
-                        pgrp = get_pid(vc->vc_tty->pgrp);
-                spin_unlock_irq(&vc->vc_tty->ctrl_lock);
-                if (pgrp) {
-                        kill_pgrp(vc->vc_tty->pgrp, SIGWINCH, 1);
-                        put_pid(pgrp);
-                }
-                *cws = ws;
+                tty_do_resize(tty, real_tty, &ws);
         }
 
         if (CON_IS_VISIBLE(vc))
@@ -932,14 +941,47 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
         return err;
 }
 
-int vc_lock_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
+/**
+ *      vc_resize               -       resize a VT
+ *      @vc: virtual console
+ *      @cols: columns
+ *      @rows: rows
+ *
+ *      Resize a virtual console as seen from the console end of things. We
+ *      use the common vc_do_resize methods to update the structures. The
+ *      caller must hold the console sem to protect console internals and
+ *      vc->vc_tty
+ */
+
+int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int rows)
+{
+        return vc_do_resize(vc->vc_tty, vc->vc_tty, vc, cols, rows);
+}
+
+/**
+ *      vt_resize               -       resize a VT
+ *      @tty: tty to resize
+ *      @real_tty: tty if a pty/tty pair
+ *      @ws: winsize attributes
+ *
+ *      Resize a virtual terminal. This is called by the tty layer as we
+ *      register our own handler for resizing. The mutual helper does all
+ *      the actual work.
+ *
+ *      Takes the console sem and the called methods then take the tty
+ *      termios_mutex and the tty ctrl_lock in that order.
+ */
+
+int vt_resize(struct tty_struct *tty, struct tty_struct *real_tty,
+        struct winsize *ws)
 {
-        int rc;
+        struct vc_data *vc = tty->driver_data;
+        int ret;
 
         acquire_console_sem();
-        rc = vc_resize(vc, cols, lines);
+        ret = vc_do_resize(tty, real_tty, vc, ws->ws_col, ws->ws_row);
         release_console_sem();
-        return rc;
+        return ret;
 }
 
 void vc_deallocate(unsigned int currcons)
@@ -2907,6 +2949,7 @@ static const struct tty_operations con_ops = {
         .start = con_start,
         .throttle = con_throttle,
         .unthrottle = con_unthrottle,
+        .resize = vt_resize,
 };
 
 int __init vty_init(void)
@@ -4061,7 +4104,6 @@ EXPORT_SYMBOL(default_blu);
 EXPORT_SYMBOL(update_region);
 EXPORT_SYMBOL(redraw_screen);
 EXPORT_SYMBOL(vc_resize);
-EXPORT_SYMBOL(vc_lock_resize);
 EXPORT_SYMBOL(fg_console);
 EXPORT_SYMBOL(console_blank_hook);
 EXPORT_SYMBOL(console_blanked);
diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index 3211afd9d57e..c904e9ad4a71 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -947,14 +947,16 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
                     get_user(cc, &vtsizes->v_cols))
                         ret = -EFAULT;
                 else {
+                        acquire_console_sem();
                         for (i = 0; i < MAX_NR_CONSOLES; i++) {
                                 vc = vc_cons[i].d;
 
                                 if (vc) {
                                         vc->vc_resize_user = 1;
-                                        vc_lock_resize(vc_cons[i].d, cc, ll);
+                                        vc_resize(vc_cons[i].d, cc, ll);
                                 }
                         }
+                        release_console_sem();
                 }
                 break;
         }
diff --git a/include/linux/tty.h b/include/linux/tty.h
index e3579cb086e0..0cbec74ec086 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -331,6 +331,8 @@ extern int tty_write_room(struct tty_struct *tty);
 extern void tty_driver_flush_buffer(struct tty_struct *tty);
 extern void tty_throttle(struct tty_struct *tty);
 extern void tty_unthrottle(struct tty_struct *tty);
+extern int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
+                                                struct winsize *ws);
 
 extern int is_current_pgrp_orphaned(void);
 extern struct pid *tty_get_pgrp(struct tty_struct *tty);
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index e1065ac0d922..16d27944c321 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -168,6 +168,18 @@
  *
  *      Optional: If not provided then the write method is called under
  *      the atomic write lock to keep it serialized with the ldisc.
+ *
+ * int (*resize)(struct tty_struct *tty, struct tty_struct *real_tty,
+ *                              unsigned int rows, unsigned int cols);
+ *
+ *      Called when a termios request is issued which changes the
+ *      requested terminal geometry.
+ *
+ *      Optional: the default action is to update the termios structure
+ *      without error. This is usually the correct behaviour. Drivers should
+ *      not force errors here if they are not resizable objects (eg a serial
+ *      line). See tty_do_resize() if you need to wrap the standard method
+ *      in your own logic - the usual case.
  */
 
 #include <linux/fs.h>
@@ -206,6 +218,8 @@ struct tty_operations {
         int (*tiocmget)(struct tty_struct *tty, struct file *file);
         int (*tiocmset)(struct tty_struct *tty, struct file *file,
                         unsigned int set, unsigned int clear);
+        int (*resize)(struct tty_struct *tty, struct tty_struct *real_tty,
+                                struct winsize *ws);
 #ifdef CONFIG_CONSOLE_POLL
         int (*poll_init)(struct tty_driver *driver, int line, char *options);
         int (*poll_get_char)(struct tty_driver *driver, int line);
diff --git a/include/linux/vt_kern.h b/include/linux/vt_kern.h
index 1c78d56c57e5..1cbd0a7db4e6 100644
--- a/include/linux/vt_kern.h
+++ b/include/linux/vt_kern.h
@@ -35,7 +35,6 @@ extern int fg_console, last_console, want_console;
 int vc_allocate(unsigned int console);
 int vc_cons_allocated(unsigned int console);
 int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines);
-int vc_lock_resize(struct vc_data *vc, unsigned int cols, unsigned int lines);
 void vc_deallocate(unsigned int console);
 void reset_palette(struct vc_data *vc);
 void do_blank_screen(int entering_gfx);