If the master and slave ptys are opened in parallel, the slave open
fails because the pty is still locked. This is as designed.
However, pty_close() is still called for the slave pty which sets
TTY_OTHER_CLOSED in the master pty. This can cause the master open
to fail as well.
Use a common pattern in other tty drivers by setting TTY_IO_ERROR
until the open is successful and only closing the pty if not set.
Note: the master pty always closes regardless of whether the open
was successful, so that proper cleanup can occur.
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/pty.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index b4e5769..6eb3e80 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -38,9 +38,12 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
if (tty->driver->subtype == PTY_TYPE_MASTER)
WARN_ON(tty->count > 1);
else {
+ if (test_bit(TTY_IO_ERROR, &tty->flags))
+ return;
if (tty->count > 2)
return;
}
+ set_bit(TTY_IO_ERROR, &tty->flags);
wake_up_interruptible(&tty->read_wait);
wake_up_interruptible(&tty->write_wait);
tty->packet = 0;
@@ -246,6 +249,8 @@ static int pty_open(struct tty_struct *tty, struct file *filp)
if (!tty || !tty->link)
goto out;
+ set_bit(TTY_IO_ERROR, &tty->flags);
+
retval = -EIO;
if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
goto out;
@@ -254,6 +259,7 @@ static int pty_open(struct tty_struct *tty, struct file *filp)
if (tty->link->count != 1)
goto out;
+ clear_bit(TTY_IO_ERROR, &tty->flags);
clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
set_bit(TTY_THROTTLED, &tty->flags);
retval = 0;
--
1.8.1.1
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