linux-kernel - [patch V4 part 1 30/36] lockdep: Always inline lockdep

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Date:   Tue, 05 May 2020 15:16:32 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [patch V4 part 1 30/36] lockdep: Always inline lockdep_{off,on}()

From: Peter Zijlstra <peterz@...radead.org>

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@...dmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 include/linux/lockdep.h  |   23 +++++++++++++++++++++--
 kernel/locking/lockdep.c |   19 -------------------
 2 files changed, 21 insertions(+), 21 deletions(-)

--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -308,8 +308,27 @@ extern void lockdep_set_selftest_task(st
 
 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);
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -393,25 +393,6 @@ void lockdep_init_task(struct task_struc
 	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))