tty: Combine SIGTTOU/SIGTTIN handling

The job_control() check in n_tty_read() has nearly identical purpose
and results as tty_check_change(). Both functions' purpose is to
determine if the current task's pgrp is the foreground pgrp for the tty,
and if not, to signal the current pgrp.

Introduce __tty_check_change() which takes the signal to send
and performs the shared operations for job control() and
tty_check_change().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 27 insertions, 46 deletions

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index ff728d32cb53..fb8ccbfdbb30 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2138,37 +2138,15 @@ extern ssize_t redirected_tty_write(struct file *, const char __user *,
 
 static int job_control(struct tty_struct *tty, struct file *file)
 {
-        struct pid *pgrp;
-
         /* Job control check -- must be done at start and after
            every sleep (POSIX.1 7.1.1.4). */
         /* NOTE: not yet done after every sleep pending a thorough
            check of the logic of this change. -- jlc */
         /* don't stop on /dev/console */
-        if (file->f_op->write == redirected_tty_write ||
-            current->signal->tty != tty)
+        if (file->f_op->write == redirected_tty_write)
                 return 0;
 
-        rcu_read_lock();
-        pgrp = task_pgrp(current);
-
-        spin_lock_irq(&tty->ctrl_lock);
-        if (!tty->pgrp)
-                printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
-        else if (pgrp != tty->pgrp) {
-                spin_unlock_irq(&tty->ctrl_lock);
-                if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned()) {
-                        rcu_read_unlock();
-                        return -EIO;
-                }
-                kill_pgrp(pgrp, SIGTTIN, 1);
-                rcu_read_unlock();
-                set_thread_flag(TIF_SIGPENDING);
-                return -ERESTARTSYS;
-        }
-        spin_unlock_irq(&tty->ctrl_lock);
-        rcu_read_unlock();
-        return 0;
+        return __tty_check_change(tty, SIGTTIN);
 }
 
 
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 2eefaa6e3e3a..aa48367a0c79 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -390,10 +390,10 @@ EXPORT_SYMBOL_GPL(tty_find_polling_driver);
  *      Locking: ctrl_lock
  */
 
-int tty_check_change(struct tty_struct *tty)
+int __tty_check_change(struct tty_struct *tty, int sig)
 {
         unsigned long flags;
-        struct pid *pgrp;
+        struct pid *pgrp, *tty_pgrp;
         int ret = 0;
 
         if (current->signal->tty != tty)
@@ -403,33 +403,35 @@ int tty_check_change(struct tty_struct *tty)
         pgrp = task_pgrp(current);
 
         spin_lock_irqsave(&tty->ctrl_lock, flags);
-
-        if (!tty->pgrp) {
-                printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
-                goto out_unlock;
-        }
-        if (pgrp == tty->pgrp)
-                goto out_unlock;
+        tty_pgrp = tty->pgrp;
         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 
-        if (is_ignored(SIGTTOU))
-                goto out_rcuunlock;
-        if (is_current_pgrp_orphaned()) {
-                ret = -EIO;
-                goto out_rcuunlock;
+        if (tty_pgrp && pgrp != tty->pgrp) {
+                if (is_ignored(sig)) {
+                        if (sig == SIGTTIN)
+                                ret = -EIO;
+                } else if (is_current_pgrp_orphaned())
+                        ret = -EIO;
+                else {
+                        kill_pgrp(pgrp, sig, 1);
+                        set_thread_flag(TIF_SIGPENDING);
+                        ret = -ERESTARTSYS;
+                }
         }
-        kill_pgrp(pgrp, SIGTTOU, 1);
-        rcu_read_unlock();
-        set_thread_flag(TIF_SIGPENDING);
-        ret = -ERESTARTSYS;
-        return ret;
-out_unlock:
-        spin_unlock_irqrestore(&tty->ctrl_lock, flags);
-out_rcuunlock:
         rcu_read_unlock();
+
+        if (!tty_pgrp) {
+                pr_warn("%s: tty_check_change: sig=%d, tty->pgrp == NULL!\n",
+                        tty_name(tty), sig);
+        }
+
         return ret;
 }
 
+int tty_check_change(struct tty_struct *tty)
+{
+        return __tty_check_change(tty, SIGTTOU);
+}
 EXPORT_SYMBOL(tty_check_change);
 
 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
diff --git a/include/linux/tty.h b/include/linux/tty.h
index c2889f4331e1..533d7f6e2481 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -423,6 +423,7 @@ extern int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
                               const char *routine);
 extern const char *tty_name(const struct tty_struct *tty);
 extern void tty_wait_until_sent(struct tty_struct *tty, long timeout);
+extern int __tty_check_change(struct tty_struct *tty, int sig);
 extern int tty_check_change(struct tty_struct *tty);
 extern void __stop_tty(struct tty_struct *tty);
 extern void stop_tty(struct tty_struct *tty);