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 8ec4d6cc7633..7417a6ca3129 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