[PATCH] lockdep: irqtrace subsystem, core

Accurate hard-IRQ-flags and softirq-flags state tracing.

This allows us to attach extra functionality to IRQ flags on/off
events (such as trace-on/off).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 23 insertions, 3 deletions

diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 114ae583cca9..b1d4332b5cf0 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -86,9 +86,6 @@ extern void synchronize_irq(unsigned int irq);
 # define synchronize_irq(irq)   barrier()
 #endif
 
-#define nmi_enter()             irq_enter()
-#define nmi_exit()              sub_preempt_count(HARDIRQ_OFFSET)
-
 struct task_struct;
 
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
@@ -97,12 +94,35 @@ static inline void account_system_vtime(struct task_struct *tsk)
 }
 #endif
 
+/*
+ * It is safe to do non-atomic ops on ->hardirq_context,
+ * because NMI handlers may not preempt and the ops are
+ * always balanced, so the interrupted value of ->hardirq_context
+ * will always be restored.
+ */
 #define irq_enter()                                     \
         do {                                            \
                 account_system_vtime(current);          \
                 add_preempt_count(HARDIRQ_OFFSET);      \
+                trace_hardirq_enter();                  \
+        } while (0)
+
+/*
+ * Exit irq context without processing softirqs:
+ */
+#define __irq_exit()                                    \
+        do {                                            \
+                trace_hardirq_exit();                   \
+                account_system_vtime(current);          \
+                sub_preempt_count(HARDIRQ_OFFSET);      \
         } while (0)
 
+/*
+ * Exit irq context and process softirqs if needed:
+ */
 extern void irq_exit(void);
 
+#define nmi_enter()             irq_enter()
+#define nmi_exit()              __irq_exit()
+
 #endif /* LINUX_HARDIRQ_H */