From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
Date: Mon, 20 Jul 2020 17:55:13 +0200
Subject: lockdep: Add preemption enabled/disabled assertion APIs
Patch-mainline: v5.9-rc1
Git-commit: 8fd8ad5c5dfcb09cf62abadd4043eaf1afbbd0ce
References: bsc#1176564 bsc#1162702 bsc#1180277
Asserting that preemption is enabled or disabled is a critical sanity
check. Developers are usually reluctant to add such a check in a
fastpath as reading the preemption count can be costly.
Extend the lockdep API with macros asserting that preemption is disabled
or enabled. If lockdep is disabled, or if the underlying architecture
does not support kernel preemption, this assert has no runtime overhead.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-8-a.darwish@linutronix.de
[dwagner: update context]
Acked-by: Daniel Wagner <dwagner@suse.de>
[dbueso: Fixed lockdep build failures, SLERT will still use task_struct]
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
include/linux/lockdep.h | 12 ++++++++++++
kernel/locking/lockdep.c | 8 ++++++++
lib/Kconfig.debug | 1 +
3 files changed, 21 insertions(+)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 981ed65f84f5..82dc9d9f5f55 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -493,12 +493,24 @@ do { \
"Not in hardirq as expected\n"); \
} while (0)
+#define lockdep_assert_preemption_enabled() \
+do { \
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) && \
+ debug_locks && \
+ (preempt_count() != 0 || \
+ !current->hardirqs_enabled)); \
+} while (0)
+
+extern void lockdep_assert_preemption_disabled(void);
#else
# define might_lock(lock) do { } while (0)
# define might_lock_read(lock) do { } while (0)
# define lockdep_assert_irqs_enabled() do { } while (0)
# define lockdep_assert_irqs_disabled() do { } while (0)
# define lockdep_assert_in_irq() do { } while (0)
+
+# define lockdep_assert_preemption_enabled() do { } while (0)
+# define lockdep_assert_preemption_disabled() do { } while (0)
#endif
#ifdef CONFIG_LOCKDEP
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index b62a9bf360f6..4d6a5115661d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -5356,3 +5356,11 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
dump_stack();
}
EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
+
+void lockdep_assert_preemption_disabled(void)
+{ WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) &&
+ debug_locks &&
+ (preempt_count() == 0 &&
+ current->hardirqs_enabled));
+}
+EXPORT_SYMBOL_GPL(lockdep_assert_preemption_disabled);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 846ede969c8b..12c8b5dbeb5a 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1098,6 +1098,7 @@ config PROVE_LOCKING
select DEBUG_RWSEMS
select DEBUG_WW_MUTEX_SLOWPATH
select DEBUG_LOCK_ALLOC
+ select PREEMPT_COUNT if !ARCH_NO_PREEMPT
select TRACE_IRQFLAGS
default n
help
--
2.26.2