With the introduction of ftrace, it is possible to recurse into
the lockdep functions via the mcount call. To prevent possible
lockups, updating the lockdep_recursion counter on grabbing the internal
lockdep_lock should prevent deadlocks.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
kernel/lockdep.c | 3 +++
1 file changed, 3 insertions(+)
Index: linux-sched-devel.git/kernel/lockdep.c
===================================================================
--- linux-sched-devel.git.orig/kernel/lockdep.c 2008-04-17 11:20:49.000000000 -0400
+++ linux-sched-devel.git/kernel/lockdep.c 2008-04-17 11:36:48.000000000 -0400
@@ -82,6 +82,8 @@ static int graph_lock(void)
__raw_spin_unlock(&lockdep_lock);
return 0;
}
+ /* prevent any recursions within lockdep from causing deadlocks */
+ current->lockdep_recursion++;
return 1;
}
@@ -90,6 +92,7 @@ static inline int graph_unlock(void)
if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
return DEBUG_LOCKS_WARN_ON(1);
+ current->lockdep_recursion--;
__raw_spin_unlock(&lockdep_lock);
return 0;
}
--
