tty: Make get_current_tty use a kref

We now return a kref covered tty reference. That ensures the tty structure
doesn't go away when you have a return from get_current_tty. This is not
enough to protect you from most of the resources being freed behind your
back - yet.

[Updated to include fixes for SELinux problems found by Andrew Morton and
 an s390 leak found while debugging the former]

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/dquot.c b/fs/dquot.c
index 8ec4d6c..7417a6c 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -897,8 +897,9 @@ static void print_warning(struct dquot *dquot, const int warntype)
 
 	mutex_lock(&tty_mutex);
 	tty = get_current_tty();
+	mutex_unlock(&tty_mutex);
 	if (!tty)
-		goto out_lock;
+		return;
 	tty_write_message(tty, dquot->dq_sb->s_id);
 	if (warntype == QUOTA_NL_ISOFTWARN || warntype == QUOTA_NL_BSOFTWARN)
 		tty_write_message(tty, ": warning, ");
@@ -926,8 +927,7 @@ static void print_warning(struct dquot *dquot, const int warntype)
 			break;
 	}
 	tty_write_message(tty, msg);
-out_lock:
-	mutex_unlock(&tty_mutex);
+	tty_kref_put(tty);
 }
 #endif