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Diffstat (limited to 'kernel/drivers/tty/pty.c')
-rw-r--r--kernel/drivers/tty/pty.c36
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);