Integrate ft_irq_fired() with Linux

This patch hooks up Feather-Trace's ft_irq_fired() handler with
Linux's interrupt handling infrastructure.

4 files changed, 26 insertions, 0 deletions

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);