linux-kernel - [tip: core/rcu] lockdep: Always inline lockdep

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Date:   Tue, 19 May 2020 19:52:35 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: core/rcu] lockdep: Always inline lockdep_{off,on}()

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     e616cb8daadf637175af4fe53138a94c190c4816
Gitweb:        https://git.kernel.org/tip/e616cb8daadf637175af4fe53138a94c190c4816
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Mon, 24 Feb 2020 22:14:51 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Tue, 19 May 2020 15:51:18 +02:00

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@...dmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>
Link: https://lkml.kernel.org/r/20200505134101.048523500@linutronix.de


---
 include/linux/lockdep.h  | 23 +++++++++++++++++++++--
 kernel/locking/lockdep.c | 19 -------------------
 2 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 206774a..8fce5c9 100644
--- a/include/linux/lockdep.h
+++ b/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);
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ac10db6..6f1c8cb 100644
--- a/kernel/locking/lockdep.c
+++ b/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))