[PATCH 5.4 090/154] lockdep: Dont disable interrupts on RT in disable_irq_nosync_lockdep.*()

Greg Kroah-Hartman
2025-04-08T12:06:14Z

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

[ Upstream commit 87886b32d669abc11c7be95ef44099215e4f5788 ]

disable_irq_nosync_lockdep() disables interrupts with lockdep enabled to
avoid false positive reports by lockdep that a certain lock has not been
acquired with disabled interrupts. The user of this macros expects that
a lock can be acquried without disabling interrupts because the IRQ line
triggering the interrupt is disabled.

This triggers a warning on PREEMPT_RT because after
disable_irq_nosync_lockdep.*() the following spinlock_t now is acquired
with disabled interrupts.

On PREEMPT_RT there is no difference between spin_lock() and
spin_lock_irq() so avoiding disabling interrupts in this case works for
the two remaining callers as of today.

Don't disable interrupts on PREEMPT_RT in disable_irq_nosync_lockdep.*().

Closes: https://lore.kernel.org/760e34f9-6034-40e0-82a5-ee9becd24438@roeck-us.net
Fixes: e8106b941ceab ("[PATCH] lockdep: core, add enable/disable_irq_irqsave/irqrestore() APIs")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Suggested-by: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20250212103619.2560503-2-bigeasy@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/interrupt.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index b70a35b97210d..7b8bdc468492e 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -411,7 +411,7 @@ irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
static inline void disable_irq_nosync_lockdep(unsigned int irq)
{
disable_irq_nosync(irq);
-#ifdef CONFIG_LOCKDEP
+#if defined(CONFIG_LOCKDEP) && !defined(CONFIG_PREEMPT_RT)
local_irq_disable();
#endif
}
@@ -419,7 +419,7 @@ static inline void disable_irq_nosync_lockdep(unsigned int irq)
static inline void disable_irq_nosync_lockdep_irqsave(unsigned int irq, unsigned long *flags)
{
disable_irq_nosync(irq);
-#ifdef CONFIG_LOCKDEP
+#if defined(CONFIG_LOCKDEP) && !defined(CONFIG_PREEMPT_RT)
local_irq_save(*flags);
#endif
}
@@ -434,7 +434,7 @@ static inline void disable_irq_lockdep(unsigned int irq)

static inline void enable_irq_lockdep(unsigned int irq)
{
-#ifdef CONFIG_LOCKDEP
+#if defined(CONFIG_LOCKDEP) && !defined(CONFIG_PREEMPT_RT)
local_irq_enable();
#endif
enable_irq(irq);
@@ -442,7 +442,7 @@ static inline void enable_irq_lockdep(unsigned int irq)

static inline void enable_irq_lockdep_irqrestore(unsigned int irq, unsigned long *flags)
{
-#ifdef CONFIG_LOCKDEP
+#if defined(CONFIG_LOCKDEP) && !defined(CONFIG_PREEMPT_RT)
local_irq_restore(*flags);
#endif
enable_irq(irq);
--
2.39.5