Merge tag 'v3.10.102' into update

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / tty / pty.c

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index abfd9908978188ffe3bfd7a9c3aa3e8c6700c5d9..85e88b8c3b290c5f2c29c119ff1d47de2cf11956 100644 (file)
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -25,7 +25,6 @@
 #include <linux/slab.h>
 #include <linux/mutex.h>
 
-
 #ifdef CONFIG_UNIX98_PTYS
 static struct tty_driver *ptm_driver;
 static struct tty_driver *pts_driver;
@@ -215,6 +214,9 @@ static int pty_signal(struct tty_struct *tty, int sig)
        unsigned long flags;
        struct pid *pgrp;
 
+       if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
+               return -EINVAL;
+
        if (tty->link) {
                spin_lock_irqsave(&tty->link->ctrl_lock, flags);
                pgrp = get_pid(tty->link->pgrp);
@@ -620,7 +622,14 @@ static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 /* this is called once with whichever end is closed last */
 static void pty_unix98_shutdown(struct tty_struct *tty)
 {
-       devpts_kill_index(tty->driver_data, tty->index);
+       struct inode *ptmx_inode;
+
+       if (tty->driver->subtype == PTY_TYPE_MASTER)
+               ptmx_inode = tty->driver_data;
+       else
+               ptmx_inode = tty->link->driver_data;
+       devpts_kill_index(ptmx_inode, tty->index);
+       devpts_del_ref(ptmx_inode);
 }
 
 static const struct tty_operations ptm_unix98_ops = {
@@ -711,6 +720,18 @@ static int ptmx_open(struct inode *inode, struct file *filp)
        set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
        tty->driver_data = inode;
 
+       /*
+        * In the case where all references to ptmx inode are dropped and we
+        * still have /dev/tty opened pointing to the master/slave pair (ptmx
+        * is closed/released before /dev/tty), we must make sure that the inode
+        * is still valid when we call the final pty_unix98_shutdown, thus we
+        * hold an additional reference to the ptmx inode. For the same /dev/tty
+        * last close case, we also need to make sure the super_block isn't
+        * destroyed (devpts instance unmounted), before /dev/tty is closed and
+        * on its release devpts_kill_index is called.
+        */
+       devpts_add_ref(inode);
+
        tty_add_file(tty, filp);
 
        slave_inode = devpts_pty_new(inode,