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>

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 0e843bf658777114a3a664e1c978588ee623cc3f..9dc46db2985e9245560223d408f9b03a05eb55b8 100644 (file)
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -238,6 +238,7 @@ extern void lockdep_info(void);
 extern void lockdep_reset(void);
 extern void lockdep_reset_lock(struct lockdep_map *lock);
 extern void lockdep_free_key_range(void *start, unsigned long size);
+extern void lockdep_sys_exit(void);
 
 extern void lockdep_off(void);
 extern void lockdep_on(void);
@@ -317,6 +318,7 @@ static inline void lockdep_on(void)
 # define INIT_LOCKDEP
 # define lockdep_reset()               do { debug_locks = 1; } while (0)
 # define lockdep_free_key_range(start, size)   do { } while (0)
+# define lockdep_sys_exit()                    do { } while (0)
 /*
  * The class key takes no space if lockdep is disabled:
  */

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 42ae4a5ab4dce0b1c38bc4edc2530ca7ca3448d6..a6f1ee9c92d9fb7900ae02e44debe938a293aedb 100644 (file)
--- 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);
+       }
+}