pty: simplify resize

We have special case logic for resizing pty/tty pairs. We also have a per
driver resize method so for the pty case we should use it.

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

6 files changed, 74 insertions, 36 deletions

diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index 0587b66d6fc7..5a8a4c28c867 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -529,7 +529,7 @@ static void hvc_set_winsz(struct work_struct *work)
         tty = tty_kref_get(hp->tty);
         spin_unlock_irqrestore(&hp->lock, hvc_flags);
 
-        tty_do_resize(tty, tty, &ws);
+        tty_do_resize(tty, &ws);
         tty_kref_put(tty);
 }
 
diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index 6d4582712b1f..b5daaaa9007e 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -230,6 +230,55 @@ static void pty_set_termios(struct tty_struct *tty,
         tty->termios->c_cflag |= (CS8 | CREAD);
 }
 
+/**
+ *      pty_do_resize           -       resize event
+ *      @tty: tty being resized
+ *      @real_tty: real tty (not the same as tty if using a pty/tty pair)
+ *      @rows: rows (character)
+ *      @cols: cols (character)
+ *
+ *      Update the termios variables and send the neccessary signals to
+ *      peform a terminal resize correctly
+ */
+
+int pty_resize(struct tty_struct *tty,  struct winsize *ws)
+{
+        struct pid *pgrp, *rpgrp;
+        unsigned long flags;
+        struct tty_struct *pty = tty->link;
+
+        /* For a PTY we need to lock the tty side */
+        mutex_lock(&tty->termios_mutex);
+        if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
+                goto done;
+
+        /* Get the PID values and reference them so we can
+           avoid holding the tty ctrl lock while sending signals.
+           We need to lock these individually however. */
+
+        spin_lock_irqsave(&tty->ctrl_lock, flags);
+        pgrp = get_pid(tty->pgrp);
+        spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+
+        spin_lock_irqsave(&pty->ctrl_lock, flags);
+        rpgrp = get_pid(pty->pgrp);
+        spin_unlock_irqrestore(&pty->ctrl_lock, flags);
+
+        if (pgrp)
+                kill_pgrp(pgrp, SIGWINCH, 1);
+        if (rpgrp != pgrp && rpgrp)
+                kill_pgrp(rpgrp, SIGWINCH, 1);
+
+        put_pid(pgrp);
+        put_pid(rpgrp);
+
+        tty->winsize = *ws;
+        pty->winsize = *ws;     /* Never used so will go away soon */
+done:
+        mutex_unlock(&tty->termios_mutex);
+        return 0;
+}
+
 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 {
         struct tty_struct *o_tty;
@@ -290,6 +339,7 @@ static const struct tty_operations pty_ops = {
         .chars_in_buffer = pty_chars_in_buffer,
         .unthrottle = pty_unthrottle,
         .set_termios = pty_set_termios,
+        .resize = pty_resize
 };
 
 /* Traditional BSD devices */
@@ -319,6 +369,7 @@ static const struct tty_operations pty_ops_bsd = {
         .unthrottle = pty_unthrottle,
         .set_termios = pty_set_termios,
         .ioctl = pty_bsd_ioctl,
+        .resize = pty_resize
 };
 
 static void __init legacy_pty_init(void)
@@ -561,7 +612,8 @@ static const struct tty_operations ptm_unix98_ops = {
         .unthrottle = pty_unthrottle,
         .set_termios = pty_set_termios,
         .ioctl = pty_unix98_ioctl,
-        .shutdown = pty_unix98_shutdown
+        .shutdown = pty_unix98_shutdown,
+        .resize = pty_resize
 };
 
 static const struct tty_operations pty_unix98_ops = {
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 2a15af65dd11..d33e5ab06177 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2048,7 +2048,6 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
 /**
  *      tty_do_resize           -       resize event
  *      @tty: tty being resized
- *      @real_tty: real tty (not the same as tty if using a pty/tty pair)
  *      @rows: rows (character)
  *      @cols: cols (character)
  *
@@ -2056,41 +2055,34 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
  *      peform a terminal resize correctly
  */
 
-int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
-                                        struct winsize *ws)
+int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
 {
-        struct pid *pgrp, *rpgrp;
+        struct pid *pgrp;
         unsigned long flags;
 
-        /* For a PTY we need to lock the tty side */
-        mutex_lock(&real_tty->termios_mutex);
-        if (!memcmp(ws, &real_tty->winsize, sizeof(*ws)))
+        /* Lock the tty */
+        mutex_lock(&tty->termios_mutex);
+        if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
                 goto done;
         /* 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);
         pgrp = get_pid(tty->pgrp);
-        rpgrp = get_pid(real_tty->pgrp);
         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 
         if (pgrp)
                 kill_pgrp(pgrp, SIGWINCH, 1);
-        if (rpgrp != pgrp && rpgrp)
-                kill_pgrp(rpgrp, SIGWINCH, 1);
-
         put_pid(pgrp);
-        put_pid(rpgrp);
 
         tty->winsize = *ws;
-        real_tty->winsize = *ws;
 done:
-        mutex_unlock(&real_tty->termios_mutex);
+        mutex_unlock(&tty->termios_mutex);
         return 0;
 }
 
 /**
  *      tiocswinsz              -       implement window size set ioctl
- *      @tty; tty
+ *      @tty; tty side of tty
  *      @arg: user buffer for result
  *
  *      Copies the user idea of the window size to the kernel. Traditionally
@@ -2103,17 +2095,16 @@ done:
  *      then calls into the default method.
  */
 
-static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
-        struct winsize __user *arg)
+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, real_tty, &tmp_ws);
+                return tty->ops->resize(tty, &tmp_ws);
         else
-                return tty_do_resize(tty, real_tty, &tmp_ws);
+                return tty_do_resize(tty, &tmp_ws);
 }
 
 /**
@@ -2538,7 +2529,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         case TIOCGWINSZ:
                 return tiocgwinsz(real_tty, p);
         case TIOCSWINSZ:
-                return tiocswinsz(tty, real_tty, p);
+                return tiocswinsz(real_tty, p);
         case TIOCCONS:
                 return real_tty != tty ? -EINVAL : tioccons(file);
         case FIONBIO:
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 639e126b2bff..80014213fb53 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -819,8 +819,8 @@ static inline int resize_screen(struct vc_data *vc, int width, int height,
  *      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)
+static int vc_do_resize(struct tty_struct *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;
@@ -932,7 +932,7 @@ static int vc_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
                 ws.ws_row = vc->vc_rows;
                 ws.ws_col = vc->vc_cols;
                 ws.ws_ypixel = vc->vc_scan_lines;
-                tty_do_resize(tty, real_tty, &ws);
+                tty_do_resize(tty, &ws);
         }
 
         if (CON_IS_VISIBLE(vc))
@@ -954,13 +954,12 @@ static int vc_do_resize(struct tty_struct *tty, struct tty_struct *real_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);
+        return vc_do_resize(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
@@ -971,14 +970,13 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int rows)
  *      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 vt_resize(struct tty_struct *tty, struct winsize *ws)
 {
         struct vc_data *vc = tty->driver_data;
         int ret;
 
         acquire_console_sem();
-        ret = vc_do_resize(tty, real_tty, vc, ws->ws_col, ws->ws_row);
+        ret = vc_do_resize(tty, vc, ws->ws_col, ws->ws_row);
         release_console_sem();
         return ret;
 }
diff --git a/include/linux/tty.h b/include/linux/tty.h
index dfc77ded198a..f88169787a5f 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -360,8 +360,7 @@ 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 tty_do_resize(struct tty_struct *tty, struct winsize *ws);
 extern void tty_shutdown(struct tty_struct *tty);
 extern void tty_free_termios(struct tty_struct *tty);
 extern int is_current_pgrp_orphaned(void);
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 78416b901589..08e088334dba 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -196,8 +196,7 @@
  *      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);
+ * int (*resize)(struct tty_struct *tty, struct winsize *ws)
  *
  *      Called when a termios request is issued which changes the
  *      requested terminal geometry.
@@ -258,8 +257,7 @@ 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);
+        int (*resize)(struct tty_struct *tty, struct winsize *ws);
         int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
 #ifdef CONFIG_CONSOLE_POLL
         int (*poll_init)(struct tty_driver *driver, int line, char *options);