Commit 21622939 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman

tty: Add diagnostic for halted line discipline

Flip buffer work must not be scheduled by the line discipline
after the line discipline has been halted; issue warning.

Note: drivers can still schedule flip buffer work.
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 91debb03
...@@ -153,6 +153,12 @@ static void n_tty_set_room(struct tty_struct *tty) ...@@ -153,6 +153,12 @@ static void n_tty_set_room(struct tty_struct *tty)
if (left && !old_left) { if (left && !old_left) {
WARN_RATELIMIT(tty->port->itty == NULL, WARN_RATELIMIT(tty->port->itty == NULL,
"scheduling with invalid itty\n"); "scheduling with invalid itty\n");
/* see if ldisc has been killed - if so, this means that
* even though the ldisc has been halted and ->buf.work
* cancelled, ->buf.work is about to be rescheduled
*/
WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
"scheduling buffer work for halted ldisc\n");
schedule_work(&tty->port->buf.work); schedule_work(&tty->port->buf.work);
} }
} }
...@@ -1624,6 +1630,8 @@ static int n_tty_open(struct tty_struct *tty) ...@@ -1624,6 +1630,8 @@ static int n_tty_open(struct tty_struct *tty)
goto err_free_bufs; goto err_free_bufs;
tty->disc_data = ldata; tty->disc_data = ldata;
/* indicate buffer work may resume */
clear_bit(TTY_LDISC_HALTED, &tty->flags);
reset_buffer_flags(tty); reset_buffer_flags(tty);
tty_unthrottle(tty); tty_unthrottle(tty);
ldata->column = 0; ldata->column = 0;
......
...@@ -375,6 +375,7 @@ static inline void tty_ldisc_put(struct tty_ldisc *ld) ...@@ -375,6 +375,7 @@ static inline void tty_ldisc_put(struct tty_ldisc *ld)
void tty_ldisc_enable(struct tty_struct *tty) void tty_ldisc_enable(struct tty_struct *tty)
{ {
clear_bit(TTY_LDISC_HALTED, &tty->flags);
set_bit(TTY_LDISC, &tty->flags); set_bit(TTY_LDISC, &tty->flags);
clear_bit(TTY_LDISC_CHANGING, &tty->flags); clear_bit(TTY_LDISC_CHANGING, &tty->flags);
wake_up(&tty_ldisc_wait); wake_up(&tty_ldisc_wait);
...@@ -513,8 +514,11 @@ static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) ...@@ -513,8 +514,11 @@ static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
static int tty_ldisc_halt(struct tty_struct *tty) static int tty_ldisc_halt(struct tty_struct *tty)
{ {
int scheduled;
clear_bit(TTY_LDISC, &tty->flags); clear_bit(TTY_LDISC, &tty->flags);
return cancel_work_sync(&tty->port->buf.work); scheduled = cancel_work_sync(&tty->port->buf.work);
set_bit(TTY_LDISC_HALTED, &tty->flags);
return scheduled;
} }
/** /**
...@@ -820,6 +824,7 @@ void tty_ldisc_hangup(struct tty_struct *tty) ...@@ -820,6 +824,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
clear_bit(TTY_LDISC, &tty->flags); clear_bit(TTY_LDISC, &tty->flags);
tty_unlock(tty); tty_unlock(tty);
cancel_work_sync(&tty->port->buf.work); cancel_work_sync(&tty->port->buf.work);
set_bit(TTY_LDISC_HALTED, &tty->flags);
mutex_unlock(&tty->ldisc_mutex); mutex_unlock(&tty->ldisc_mutex);
retry: retry:
tty_lock(tty); tty_lock(tty);
......
...@@ -315,6 +315,7 @@ struct tty_file_private { ...@@ -315,6 +315,7 @@ struct tty_file_private {
#define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */ #define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */
#define TTY_HUPPED 18 /* Post driver->hangup() */ #define TTY_HUPPED 18 /* Post driver->hangup() */
#define TTY_HUPPING 21 /* ->hangup() in progress */ #define TTY_HUPPING 21 /* ->hangup() in progress */
#define TTY_LDISC_HALTED 22 /* Line discipline is halted */
#define TTY_WRITE_FLUSH(tty) tty_write_flush((tty)) #define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
......
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