tty: Refactor session leader SIGHUP from __tty_hangup()

Reduce complexity of __tty_hangup(); separate SIGHUP signalling
into tty_signal_session_leader().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 50 insertions, 31 deletions

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 05400acbc456..706c23b9cb95 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -533,6 +533,51 @@ void tty_wakeup(struct tty_struct *tty)
 EXPORT_SYMBOL_GPL(tty_wakeup);
 
 /**
+ *      tty_signal_session_leader       - sends SIGHUP to session leader
+ *
+ *      Send SIGHUP and SIGCONT to the session leader and its
+ *      process group.
+ *
+ *      Returns the number of processes in the session with this tty
+ *      as their controlling terminal. This value is used to drop
+ *      tty references for those processes.
+ */
+static int tty_signal_session_leader(struct tty_struct *tty)
+{
+        struct task_struct *p;
+        unsigned long flags;
+        int refs = 0;
+
+        read_lock(&tasklist_lock);
+        if (tty->session) {
+                do_each_pid_task(tty->session, PIDTYPE_SID, p) {
+                        spin_lock_irq(&p->sighand->siglock);
+                        if (p->signal->tty == tty) {
+                                p->signal->tty = NULL;
+                                /* We defer the dereferences outside fo
+                                   the tasklist lock */
+                                refs++;
+                        }
+                        if (!p->signal->leader) {
+                                spin_unlock_irq(&p->sighand->siglock);
+                                continue;
+                        }
+                        __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
+                        __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
+                        put_pid(p->signal->tty_old_pgrp);  /* A noop */
+                        spin_lock_irqsave(&tty->ctrl_lock, flags);
+                        if (tty->pgrp)
+                                p->signal->tty_old_pgrp = get_pid(tty->pgrp);
+                        spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+                        spin_unlock_irq(&p->sighand->siglock);
+                } while_each_pid_task(tty->session, PIDTYPE_SID, p);
+        }
+        read_unlock(&tasklist_lock);
+
+        return refs;
+}
+
+/**
  *      __tty_hangup            -       actual handler for hangup events
  *      @work: tty device
  *
@@ -558,11 +603,10 @@ static void __tty_hangup(struct tty_struct *tty)
 {
         struct file *cons_filp = NULL;
         struct file *filp, *f = NULL;
-        struct task_struct *p;
         struct tty_file_private *priv;
         int    closecount = 0, n;
         unsigned long flags;
-        int refs = 0;
+        int refs;
 
         if (!tty)
                 return;
@@ -605,31 +649,10 @@ static void __tty_hangup(struct tty_struct *tty)
          */
         tty_ldisc_hangup(tty);
 
-        read_lock(&tasklist_lock);
-        if (tty->session) {
-                do_each_pid_task(tty->session, PIDTYPE_SID, p) {
-                        spin_lock_irq(&p->sighand->siglock);
-                        if (p->signal->tty == tty) {
-                                p->signal->tty = NULL;
-                                /* We defer the dereferences outside fo
-                                   the tasklist lock */
-                                refs++;
-                        }
-                        if (!p->signal->leader) {
-                                spin_unlock_irq(&p->sighand->siglock);
-                                continue;
-                        }
-                        __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
-                        __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
-                        put_pid(p->signal->tty_old_pgrp);  /* A noop */
-                        spin_lock_irqsave(&tty->ctrl_lock, flags);
-                        if (tty->pgrp)
-                                p->signal->tty_old_pgrp = get_pid(tty->pgrp);
-                        spin_unlock_irqrestore(&tty->ctrl_lock, flags);
-                        spin_unlock_irq(&p->sighand->siglock);
-                } while_each_pid_task(tty->session, PIDTYPE_SID, p);
-        }
-        read_unlock(&tasklist_lock);
+        refs = tty_signal_session_leader(tty);
+        /* Account for the p->signal references we killed */
+        while (refs--)
+                tty_kref_put(tty);
 
         spin_lock_irqsave(&tty->ctrl_lock, flags);
         clear_bit(TTY_THROTTLED, &tty->flags);
@@ -642,10 +665,6 @@ static void __tty_hangup(struct tty_struct *tty)
         tty->ctrl_status = 0;
         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 
-        /* Account for the p->signal references we killed */
-        while (refs--)
-                tty_kref_put(tty);
-
         /*
          * If one of the devices matches a console pointer, we
          * cannot just call hangup() because that will cause