From 5ef7e2dad47bce26ce3afd0c402f6cc185e75ad6 Mon Sep 17 00:00:00 2001
From: Bjoern Brandenburg <bbb@mpi-sws.org>
Date: Sun, 23 Jun 2013 14:51:57 +0200
Subject: Integrate ft_irq_fired() with Linux

This patch hooks up Feather-Trace's ft_irq_fired() handler with
Linux's interrupt handling infrastructure.
---
 include/linux/hardirq.h    |  4 ++++
 include/litmus/trace_irq.h | 14 ++++++++++++++
 kernel/sched/core.c        |  5 +++++
 kernel/softirq.c           |  3 +++
 4 files changed, 26 insertions(+)
 create mode 100644 include/litmus/trace_irq.h

diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index c1d6555d2567..7ad5fd87d6d4 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -7,6 +7,8 @@
 #include <linux/vtime.h>
 #include <asm/hardirq.h>
 
+#include <litmus/trace_irq.h>
+
 /*
  * We put the hardirq and softirq counter into the preemption
  * counter. The bitmask has the following meaning:
@@ -154,6 +156,7 @@ extern void rcu_nmi_exit(void);
 		account_irq_enter_time(current);	\
 		add_preempt_count(HARDIRQ_OFFSET);	\
 		trace_hardirq_enter();			\
+		ft_irq_fired();				\
 	} while (0)
 
 /*
@@ -184,6 +187,7 @@ extern void irq_exit(void);
 		add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
 		rcu_nmi_enter();				\
 		trace_hardirq_enter();				\
+		ft_irq_fired();					\
 	} while (0)
 
 #define nmi_exit()						\
diff --git a/include/litmus/trace_irq.h b/include/litmus/trace_irq.h
new file mode 100644
index 000000000000..0d0c042ba9c3
--- /dev/null
+++ b/include/litmus/trace_irq.h
@@ -0,0 +1,14 @@
+#ifndef _LITMUS_TRACE_IRQ_H_
+#define	_LITMUS_TRACE_IRQ_H_
+
+#ifdef CONFIG_SCHED_OVERHEAD_TRACE
+
+void ft_irq_fired(void);
+
+#else
+
+#define ft_irq_fired() /* nothing to do */
+
+#endif
+
+#endif
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e8b335016c52..a4c8c093f6bc 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1408,7 +1408,12 @@ void scheduler_ipi(void)
 	if (llist_empty(&this_rq()->wake_list)
 			&& !tick_nohz_full_cpu(smp_processor_id())
 			&& !got_nohz_idle_kick())
+	{
+		/* If we don't call irq_enter(), we need to triggger the IRQ
+		 * tracing manually. */
+		ft_irq_fired();
 		return;
+	}
 
 	/*
 	 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 3d6833f125d3..746010e5f523 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -226,6 +226,9 @@ asmlinkage void __do_softirq(void)
 	 */
 	current->flags &= ~PF_MEMALLOC;
 
+	/* Mark Feather-Trace samples as "disturbed". */
+	ft_irq_fired();
+
 	pending = local_softirq_pending();
 	account_irq_enter_time(current);
 
-- 
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