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n_tty: Buffer work should not reschedule itself

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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>
This commit is contained in:
Peter Hurley 2013-06-15 07:28:31 -04:00 committed by Greg Kroah-Hartman
parent b848305276
commit 7879a9f9fd
1 changed files with 9 additions and 4 deletions
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13
drivers/tty/n_tty.c
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@ -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)) {