diff options
author | Anton Blanchard <anton@samba.org> | 2010-04-06 21:42:38 +1000 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-01-07 14:43:12 -0800 |
commit | ec955e326e90b693011f6429b4cc0a72fe795168 (patch) | |
tree | 7c596d19a7af444f2e70d92569dcb7c81489d5da /drivers | |
parent | ef5ce99dff0b45abd4563de36c0bc32ba00ae022 (diff) |
hvc_console: Fix race between hvc_close and hvc_remove, again
commit 320718ee074acce5ffced6506cb51af1388942aa upstream.
I don't claim to understand the tty layer, but it seems like hvc_open and
hvc_close should be balanced in their kref reference counting.
Right now we get a kref every call to hvc_open:
if (hp->count++ > 0) {
tty_kref_get(tty); <----- here
spin_unlock_irqrestore(&hp->lock, flags);
hvc_kick();
return 0;
} /* else count == 0 */
tty->driver_data = hp;
hp->tty = tty_kref_get(tty); <------ or here if hp->count was 0
But hvc_close has:
tty_kref_get(tty);
if (--hp->count == 0) {
...
/* Put the ref obtained in hvc_open() */
tty_kref_put(tty);
...
}
tty_kref_put(tty);
Since the outside kref get/put balance we only do a single kref_put when
count reaches 0.
The patch below changes things to call tty_kref_put once for every
hvc_close call, and with that my machine boots fine.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/char/hvc_console.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c index 1f714d16a2ba..f05e0fad171e 100644 --- a/drivers/char/hvc_console.c +++ b/drivers/char/hvc_console.c @@ -367,16 +367,12 @@ static void hvc_close(struct tty_struct *tty, struct file * filp) hp = tty->driver_data; spin_lock_irqsave(&hp->lock, flags); - tty_kref_get(tty); if (--hp->count == 0) { /* We are done with the tty pointer now. */ hp->tty = NULL; spin_unlock_irqrestore(&hp->lock, flags); - /* Put the ref obtained in hvc_open() */ - tty_kref_put(tty); - if (hp->ops->notifier_del) hp->ops->notifier_del(hp, hp->data); |