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path: root/drivers/tty/tty_ldisc.c
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Diffstat (limited to 'drivers/tty/tty_ldisc.c')
-rw-r--r--drivers/tty/tty_ldisc.c92
1 files changed, 21 insertions, 71 deletions
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 68947f6de5ad..b0500a0a87b8 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -271,10 +271,13 @@ const struct file_operations tty_ldiscs_proc_fops = {
struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
{
+ struct tty_ldisc *ld;
+
ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT);
- if (!tty->ldisc)
+ ld = tty->ldisc;
+ if (!ld)
ldsem_up_read(&tty->ldisc_sem);
- return tty->ldisc;
+ return ld;
}
EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
@@ -489,41 +492,6 @@ static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld)
}
/**
- * tty_ldisc_restore - helper for tty ldisc change
- * @tty: tty to recover
- * @old: previous ldisc
- *
- * Restore the previous line discipline or N_TTY when a line discipline
- * change fails due to an open error
- */
-
-static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
-{
- struct tty_ldisc *new_ldisc;
- int r;
-
- /* There is an outstanding reference here so this is safe */
- old = tty_ldisc_get(tty, old->ops->num);
- WARN_ON(IS_ERR(old));
- tty->ldisc = old;
- tty_set_termios_ldisc(tty, old->ops->num);
- if (tty_ldisc_open(tty, old) < 0) {
- tty_ldisc_put(old);
- /* This driver is always present */
- new_ldisc = tty_ldisc_get(tty, N_TTY);
- if (IS_ERR(new_ldisc))
- panic("n_tty: get");
- tty->ldisc = new_ldisc;
- tty_set_termios_ldisc(tty, N_TTY);
- r = tty_ldisc_open(tty, new_ldisc);
- if (r < 0)
- panic("Couldn't open N_TTY ldisc for "
- "%s --- error %d.",
- tty_name(tty), r);
- }
-}
-
-/**
* tty_set_ldisc - set line discipline
* @tty: the terminal to set
* @ldisc: the line discipline
@@ -536,12 +504,7 @@ static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
int tty_set_ldisc(struct tty_struct *tty, int disc)
{
- int retval;
- struct tty_ldisc *old_ldisc, *new_ldisc;
-
- new_ldisc = tty_ldisc_get(tty, disc);
- if (IS_ERR(new_ldisc))
- return PTR_ERR(new_ldisc);
+ int retval, old_disc;
tty_lock(tty);
retval = tty_ldisc_lock(tty, 5 * HZ);
@@ -554,7 +517,8 @@ int tty_set_ldisc(struct tty_struct *tty, int disc)
}
/* Check the no-op case */
- if (tty->ldisc->ops->num == disc)
+ old_disc = tty->ldisc->ops->num;
+ if (old_disc == disc)
goto out;
if (test_bit(TTY_HUPPED, &tty->flags)) {
@@ -563,34 +527,25 @@ int tty_set_ldisc(struct tty_struct *tty, int disc)
goto out;
}
- old_ldisc = tty->ldisc;
-
- /* Shutdown the old discipline. */
- tty_ldisc_close(tty, old_ldisc);
-
- /* Now set up the new line discipline. */
- tty->ldisc = new_ldisc;
- tty_set_termios_ldisc(tty, disc);
-
- retval = tty_ldisc_open(tty, new_ldisc);
+ retval = tty_ldisc_reinit(tty, disc);
if (retval < 0) {
/* Back to the old one or N_TTY if we can't */
- tty_ldisc_put(new_ldisc);
- tty_ldisc_restore(tty, old_ldisc);
+ if (tty_ldisc_reinit(tty, old_disc) < 0) {
+ pr_err("tty: TIOCSETD failed, reinitializing N_TTY\n");
+ if (tty_ldisc_reinit(tty, N_TTY) < 0) {
+ /* At this point we have tty->ldisc == NULL. */
+ pr_err("tty: reinitializing N_TTY failed\n");
+ }
+ }
}
- if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) {
+ if (tty->ldisc && tty->ldisc->ops->num != old_disc &&
+ tty->ops->set_ldisc) {
down_read(&tty->termios_rwsem);
tty->ops->set_ldisc(tty);
up_read(&tty->termios_rwsem);
}
- /* At this point we hold a reference to the new ldisc and a
- reference to the old ldisc, or we hold two references to
- the old ldisc (if it was restored as part of error cleanup
- above). In either case, releasing a single reference from
- the old ldisc is correct. */
- new_ldisc = old_ldisc;
out:
tty_ldisc_unlock(tty);
@@ -598,7 +553,6 @@ out:
already running */
tty_buffer_restart_work(tty->port);
err:
- tty_ldisc_put(new_ldisc); /* drop the extra reference */
tty_unlock(tty);
return retval;
}
@@ -659,10 +613,8 @@ int tty_ldisc_reinit(struct tty_struct *tty, int disc)
int retval;
ld = tty_ldisc_get(tty, disc);
- if (IS_ERR(ld)) {
- BUG_ON(disc == N_TTY);
+ if (IS_ERR(ld))
return PTR_ERR(ld);
- }
if (tty->ldisc) {
tty_ldisc_close(tty, tty->ldisc);
@@ -674,10 +626,8 @@ int tty_ldisc_reinit(struct tty_struct *tty, int disc)
tty_set_termios_ldisc(tty, disc);
retval = tty_ldisc_open(tty, tty->ldisc);
if (retval) {
- if (!WARN_ON(disc == N_TTY)) {
- tty_ldisc_put(tty->ldisc);
- tty->ldisc = NULL;
- }
+ tty_ldisc_put(tty->ldisc);
+ tty->ldisc = NULL;
}
return retval;
}