From f18f9498e90327b9b0e245e191029e6e1996d203 Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Mon, 30 Nov 2009 13:18:35 +0000
Subject: [PATCH] tty: Push the lock down further into the ldisc code
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/char/tty_io.c | 2 --
drivers/char/tty_ldisc.c | 12 +++++++++---
2 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 1e2413093615b..c408c81c06a09 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1347,9 +1347,7 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
* If we fail here just call release_tty to clean up. No need
* to decrement the use counts, as release_tty doesn't care.
*/
- lock_kernel();
retval = tty_ldisc_setup(tty, tty->link);
- unlock_kernel();
if (retval)
goto release_mem_out;
return tty;
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index d914e77f7f016..3f653f7d849f0 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -445,8 +445,14 @@ static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
{
WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags));
- if (ld->ops->open)
- return ld->ops->open(tty);
+ if (ld->ops->open) {
+ int ret;
+ /* BKL here locks verus a hangup event */
+ lock_kernel();
+ ret = ld->ops->open(tty);
+ unlock_kernel();
+ return ret;
+ }
return 0;
}
@@ -566,6 +572,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
return 0;
}
+ unlock_kernel();
/*
* Problem: What do we do if this blocks ?
* We could deadlock here
@@ -573,7 +580,6 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty_wait_until_sent(tty, 0);
- unlock_kernel();
mutex_lock(&tty->ldisc_mutex);
/*
--
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