lockdep: Always inline lockdep_{off,on}()

These functions are called {early,late} in nmi_{enter,exit} and should
not be traced or probed. They are also puny, so 'inline' them.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134101.048523500@linutronix.de

include/linux/lockdep.h

@@ -308,8 +308,27 @@ extern void lockdep_set_selftest_task(struct task_struct *task);
 
 extern void lockdep_init_task(struct task_struct *task);
 
-extern void lockdep_off(void);
-extern void lockdep_on(void);
+/*
+ * Split the recrursion counter in two to readily detect 'off' vs recursion.
+ */
+#define LOCKDEP_RECURSION_BITS	16
+#define LOCKDEP_OFF		(1U << LOCKDEP_RECURSION_BITS)
+#define LOCKDEP_RECURSION_MASK	(LOCKDEP_OFF - 1)
+
+/*
+ * lockdep_{off,on}() are macros to avoid tracing and kprobes; not inlines due
+ * to header dependencies.
+ */
+
+#define lockdep_off()					\
+do {							\
+	current->lockdep_recursion += LOCKDEP_OFF;	\
+} while (0)
+
+#define lockdep_on()					\
+do {							\
+	current->lockdep_recursion -= LOCKDEP_OFF;	\
+} while (0)
 
 extern void lockdep_register_key(struct lock_class_key *key);
 extern void lockdep_unregister_key(struct lock_class_key *key);

kernel/locking/lockdep.c

@@ -393,25 +393,6 @@ void lockdep_init_task(struct task_struct *task)
 	task->lockdep_recursion = 0;
 }
 
-/*
- * Split the recrursion counter in two to readily detect 'off' vs recursion.
- */
-#define LOCKDEP_RECURSION_BITS	16
-#define LOCKDEP_OFF		(1U << LOCKDEP_RECURSION_BITS)
-#define LOCKDEP_RECURSION_MASK	(LOCKDEP_OFF - 1)
-
-void lockdep_off(void)
-{
-	current->lockdep_recursion += LOCKDEP_OFF;
-}
-EXPORT_SYMBOL(lockdep_off);
-
-void lockdep_on(void)
-{
-	current->lockdep_recursion -= LOCKDEP_OFF;
-}
-EXPORT_SYMBOL(lockdep_on);
-
 static inline void lockdep_recursion_finish(void)
 {
 	if (WARN_ON_ONCE(--current->lockdep_recursion))