Messages in this thread Patch in this message | | | Date | Thu, 17 Apr 2008 12:24:35 -0400 (EDT) | From | Steven Rostedt <> | Subject | [RFC PATCH] lockdep: update lockdep_recursion on graph_lock |
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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; }
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