Messages in this thread Patch in this message | | | From | Peter Hurley <> | Subject | [PATCH v2 13/14] tty: Hold termios_rwsem for tcflow(TCIxxx) | Date | Wed, 10 Sep 2014 15:06:35 -0400 |
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While transmitting a START/STOP char for tcflow(TCION/TCIOFF), prevent a termios change. Otherwise, a garbage in-band flow control char may be sent, if the termios change overlaps the transmission setup.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> --- drivers/tty/tty_ioctl.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c index 14d9002..32cee97 100644 --- a/drivers/tty/tty_ioctl.c +++ b/drivers/tty/tty_ioctl.c @@ -1164,17 +1164,21 @@ int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file, spin_unlock_irq(&tty->flow_lock); break; case TCIOFF: + down_read(&tty->termios_rwsem); if (STOP_CHAR(tty) != __DISABLED_CHAR) - return tty_send_xchar(tty, STOP_CHAR(tty)); + retval = tty_send_xchar(tty, STOP_CHAR(tty)); + up_read(&tty->termios_rwsem); break; case TCION: + down_read(&tty->termios_rwsem); if (START_CHAR(tty) != __DISABLED_CHAR) - return tty_send_xchar(tty, START_CHAR(tty)); + retval = tty_send_xchar(tty, START_CHAR(tty)); + up_read(&tty->termios_rwsem); break; default: return -EINVAL; } - return 0; + return retval; case TCFLSH: retval = tty_check_change(tty); if (retval) -- 2.1.0
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