[RFC PATCH 3/3] irqflags: Warn on irq disable when disabled and enable when enabled

[Nicholas Piggin <npiggin@gmail.com>]

Add CONFIG_IRQFLAGS_DEBUG checks for local_irq_disable() when irqs
are already disabled, and local_irq_enable() when they are enabled.
This could help catch risky or unbalanced irq manipulation.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 include/linux/irqflags.h       | 26 ++++++++++++++++++++++++--
 kernel/locking/irqflag-debug.c | 14 ++++++++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
index 5ec0fa71399e..82f54cda2c20 100644
--- a/include/linux/irqflags.h
+++ b/include/linux/irqflags.h
@@ -157,6 +157,18 @@ do {						\
 #endif
 
 #ifdef CONFIG_DEBUG_IRQFLAGS
+extern void warn_bogus_irq_disable(void);
+#define raw_check_bogus_irq_disable()			\
+	do {						\
+		if (unlikely(arch_irqs_disabled()))	\
+			warn_bogus_irq_disable();	\
+	} while (0)
+extern void warn_bogus_irq_enable(void);
+#define raw_check_bogus_irq_enable()			\
+	do {						\
+		if (unlikely(!arch_irqs_disabled()))	\
+			warn_bogus_irq_enable();	\
+	} while (0)
 extern void warn_bogus_irq_restore(void);
 #define raw_check_bogus_irq_restore()			\
 	do {						\
@@ -164,14 +176,24 @@ extern void warn_bogus_irq_restore(void);
 			warn_bogus_irq_restore();	\
 	} while (0)
 #else
+#define raw_check_bogus_irq_disable() do { } while (0)
+#define raw_check_bogus_irq_enable() do { } while (0)
 #define raw_check_bogus_irq_restore() do { } while (0)
 #endif
 
 /*
  * Wrap the arch provided IRQ routines to provide appropriate checks.
  */
-#define raw_local_irq_disable()		arch_local_irq_disable()
-#define raw_local_irq_enable()		arch_local_irq_enable()
+#define raw_local_irq_disable()				\
+	do {						\
+		raw_check_bogus_irq_disable();		\
+		arch_local_irq_disable();		\
+	} while (0)
+#define raw_local_irq_enable()				\
+	do {						\
+		raw_check_bogus_irq_enable();		\
+		arch_local_irq_enable();		\
+	} while (0)
 #define raw_local_irq_save(flags)			\
 	do {						\
 		typecheck(unsigned long, flags);	\
diff --git a/kernel/locking/irqflag-debug.c b/kernel/locking/irqflag-debug.c
index 810b50344d35..20e5e1b9a86f 100644
--- a/kernel/locking/irqflag-debug.c
+++ b/kernel/locking/irqflag-debug.c
@@ -4,6 +4,20 @@
 #include <linux/export.h>
 #include <linux/irqflags.h>
 
+noinstr void warn_bogus_irq_disable(void)
+{
+	instrumentation_begin();
+	WARN_ONCE(1, "raw_local_irq_disable() called with IRQs disabled\n");
+	instrumentation_end();
+}
+EXPORT_SYMBOL(warn_bogus_irq_disable);
+noinstr void warn_bogus_irq_enable(void)
+{
+	instrumentation_begin();
+	WARN_ONCE(1, "raw_local_irq_enable() called with IRQs enabled\n");
+	instrumentation_end();
+}
+EXPORT_SYMBOL(warn_bogus_irq_enable);
 noinstr void warn_bogus_irq_restore(void)
 {
 	instrumentation_begin();
-- 
2.40.1