lockdep: syscall exit check

Provide a check to validate that we do not hold any locks when switching
back to user-space.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 16 insertions, 0 deletions

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 42ae4a5ab4dc..a6f1ee9c92d9 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -3199,3 +3199,19 @@ void debug_show_held_locks(struct task_struct *task)
 }
 
 EXPORT_SYMBOL_GPL(debug_show_held_locks);
+
+void lockdep_sys_exit(void)
+{
+        struct task_struct *curr = current;
+
+        if (unlikely(curr->lockdep_depth)) {
+                if (!debug_locks_off())
+                        return;
+                printk("\n================================================\n");
+                printk(  "[ BUG: lock held when returning to user space! ]\n");
+                printk(  "------------------------------------------------\n");
+                printk("%s/%d is leaving the kernel with locks still held!\n",
+                                curr->comm, curr->pid);
+                lockdep_print_held_locks(curr);
+        }
+}