These changes are the raw update to linux-4.4.6-rt14. Kernel sources

are taken from kernel.org, and rt patch from the rt wiki download page.

During the rebasing, the following patch collided:

Force tick interrupt and get rid of softirq magic(I70131fb85).

Collisions have been removed because its logic was found on the
source already.

Change-Id: I7f57a4081d9deaa0d9ccfc41a6c8daccdee3b769
Signed-off-by: José Pekkarinen <jose.pekkarinen@nokia.com>

1 files changed, 33 insertions, 3 deletions

diff --git a/kernel/drivers/tty/pty.c b/kernel/drivers/tty/pty.c
index 4d5e84097..78e983677 100644
--- a/kernel/drivers/tty/pty.c
+++ b/kernel/drivers/tty/pty.c
@@ -7,7 +7,6 @@
  */
 
 #include <linux/module.h>
-
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/tty.h>
@@ -26,6 +25,12 @@
 #include <linux/mutex.h>
 #include <linux/poll.h>
 
+#undef TTY_DEBUG_HANGUP
+#ifdef TTY_DEBUG_HANGUP
+# define tty_debug_hangup(tty, f, args...)	tty_debug(tty, f, ##args)
+#else
+# define tty_debug_hangup(tty, f, args...)	do {} while (0)
+#endif
 
 #ifdef CONFIG_UNIX98_PTYS
 static struct tty_driver *ptm_driver;
@@ -495,6 +500,10 @@ static int pty_bsd_ioctl(struct tty_struct *tty,
 }
 
 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
+/*
+ * not really modular, but the easiest way to keep compat with existing
+ * bootargs behaviour is to continue using module_param here.
+ */
 module_param(legacy_count, int, 0);
 
 /*
@@ -672,7 +681,14 @@ 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 = {
@@ -764,6 +780,18 @@ 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,
@@ -779,6 +807,8 @@ static int ptmx_open(struct inode *inode, struct file *filp)
 	if (retval)
 		goto err_release;
 
+	tty_debug_hangup(tty, "(tty count=%d)\n", tty->count);
+
 	tty_unlock(tty);
 	return 0;
 err_release:
@@ -869,4 +899,4 @@ static int __init pty_init(void)
 	unix98_pty_init();
 	return 0;
 }
-module_init(pty_init);
+device_initcall(pty_init);