diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2013-06-15 13:28:31 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-06-17 21:55:30 +0200 |
| commit | 7879a9f9fd4ff4a88b3c51f4ab6718dc7f86ed86 (patch) | |
| tree | e983db0f0fcf544201b3e457f616ac3c909bbac4 /drivers/tty/n_tty.c | |
| parent | n_tty: Fix unsafe update of available buffer space (diff) | |
| download | linux-7879a9f9fd4ff4a88b3c51f4ab6718dc7f86ed86.tar.xz linux-7879a9f9fd4ff4a88b3c51f4ab6718dc7f86ed86.zip | |
n_tty: Buffer work should not reschedule itself
Although the driver-side input path must update the available
buffer space, it should not reschedule itself. If space is still
available and the flip buffers are not empty, flush_to_ldisc()
will loop again.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_tty.c')
| -rw-r--r-- | drivers/tty/n_tty.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 064616542cb5..4bf0fc0843d7 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -118,14 +118,14 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x, * n_tty_set_room - receive space * @tty: terminal * - * Sets tty->receive_room to reflect the currently available space + * Updates tty->receive_room to reflect the currently available space * in the input buffer, and re-schedules the flip buffer work if space * just became available. * * Locks: Concurrent update is protected with read_lock */ -static void n_tty_set_room(struct tty_struct *tty) +static int set_room(struct tty_struct *tty) { struct n_tty_data *ldata = tty->disc_data; int left; @@ -155,8 +155,13 @@ static void n_tty_set_room(struct tty_struct *tty) raw_spin_unlock_irqrestore(&ldata->read_lock, flags); + return left && !old_left; +} + +static void n_tty_set_room(struct tty_struct *tty) +{ /* Did this open up the receive buffer? We may need to flip */ - if (left && !old_left) { + if (set_room(tty)) { WARN_RATELIMIT(tty->port->itty == NULL, "scheduling with invalid itty\n"); /* see if ldisc has been killed - if so, this means that @@ -1459,7 +1464,7 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, tty->ops->flush_chars(tty); } - n_tty_set_room(tty); + set_room(tty); if ((!ldata->icanon && (ldata->read_cnt >= ldata->minimum_to_wake)) || L_EXTPROC(tty)) { |