Scheduler instrumentation: Fix some associated with monitoring critical sections

include/nuttx/irq.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * include/nuttx/irq.h
  *
- *   Copyright (C) 2007-2011, 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2011, 2013, 2016 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -113,7 +113,7 @@ int irq_attach(int irq, xcpt_t isr);
  *
  ****************************************************************************/
 
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) || defined(CONFIG_SCHED_INSTRUMENTATION_CSECTION)
 irqstate_t enter_critical_section(void);
 #else
 #  define enter_critical_section(f) up_irq_save(f)
@@ -131,7 +131,7 @@ irqstate_t enter_critical_section(void);
  *
  ****************************************************************************/
 
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) || defined(CONFIG_SCHED_INSTRUMENTATION_CSECTION)
 void leave_critical_section(irqstate_t flags);
 #else
 #  define leave_critical_section(f) up_irq_restore(f)
@@ -144,4 +144,3 @@ void leave_critical_section(irqstate_t flags);
 #endif
 
 #endif /* __INCLUDE_NUTTX_IRQ_H */
-

sched/Kconfig

@@ -627,7 +627,7 @@ config SCHED_INSTRUMENTATION_PREEMPTION
 config SCHED_INSTRUMENTATION_CSECTION
 	bool "Critical section monitor hooks"
 	default n
-	depends on SMP
+	depends on EXPERIMENTAL
 	---help---
 		Enables additional hooks for entry and exit from critical sections.
 		Interrupts are disabled while within a critical section.  Board-
@@ -635,6 +635,13 @@ config SCHED_INSTRUMENTATION_CSECTION
 
 			void sched_note_csection(FAR struct tcb_s *tcb, bool state);
 
+		NOTE: This option is marked EXPERIMENTAL because there is a logical
+		error in the design.  That error is that sched_note_get() calls
+		enter/leave_critical_section.  When the buffer note buffer has been
+		filled, each of these calls causes an entry to be removed from the
+		note buffer to make more space.  The end result is that every other
+		note is lost when dumping the note buffer.  Not very useful!
+
 config SCHED_INSTRUMENTATION_BUFFER
 	bool "Buffer instrumentation data in memory"
 	default n

sched/irq/Make.defs

@@ -37,6 +37,8 @@ CSRCS += irq_initialize.c irq_attach.c irq_dispatch.c irq_unexpectedisr.c
 
 ifeq ($(CONFIG_SMP),y)
 CSRCS += irq_csection.c
+else ifeq ($(CONFIG_SCHED_INSTRUMENTATION_CSECTION),y)
+CSRCS += irq_csection.c
 endif
 
 # Include irq build support

sched/irq/irq_csection.c

@@ -48,11 +48,13 @@
 #include "sched/sched.h"
 #include "irq/irq.h"
 
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) || defined(CONFIG_SCHED_INSTRUMENTATION_CSECTION)
 
 /****************************************************************************
  * Public Data
  ****************************************************************************/
+
+#ifdef CONFIG_SMP
 /* This is the spinlock that enforces critical sections when interrupts are
  * disabled.
  */
@@ -63,6 +65,7 @@ volatile spinlock_t g_cpu_irqlock = SP_UNLOCKED;
 
 volatile spinlock_t g_cpu_irqsetlock;
 volatile cpu_set_t g_cpu_irqset;
+#endif
 
 /****************************************************************************
  * Public Functions
@@ -78,6 +81,7 @@ volatile cpu_set_t g_cpu_irqset;
  *
  ****************************************************************************/
 
+#ifdef CONFIG_SMP
 irqstate_t enter_critical_section(void)
 {
   FAR struct tcb_s *rtcb;
@@ -96,6 +100,8 @@ irqstate_t enter_critical_section(void)
   /* Do we already have interrupts disabled? */
 
   rtcb = this_task();
+  DEBUGASSERT(rtcb != NULL);
+
   if (rtcb->irqcount > 0)
     {
       /* Yes... make sure that the spinlock is set and increment the IRQ
@@ -136,6 +142,26 @@ irqstate_t enter_critical_section(void)
 
   return up_irq_save();
 }
+#else /* defined(CONFIG_SCHED_INSTRUMENTATION_CSECTION) */
+irqstate_t enter_critical_section(void)
+{
+  /* Check if we were called from an interrupt handler */
+
+  if (!up_interrupt_context())
+    {
+      FAR struct tcb_s *rtcb = this_task();
+      DEBUGASSERT(rtcb != NULL);
+
+      /* No.. note that we have entered the critical section */
+
+      sched_note_csection(rtcb, true);
+    }
+
+  /* And disable interrupts */
+
+  return up_irq_save();
+}
+#endif
 
 /****************************************************************************
  * Name: leave_critical_section
@@ -146,6 +172,7 @@ irqstate_t enter_critical_section(void)
  *
  ****************************************************************************/
 
+#ifdef CONFIG_SMP
 void leave_critical_section(irqstate_t flags)
 {
   /* Do nothing if called from an interrupt handler */
@@ -153,8 +180,7 @@ void leave_critical_section(irqstate_t flags)
   if (!up_interrupt_context())
     {
       FAR struct tcb_s *rtcb = this_task();
-
+      DEBUGASSERT(rtcb != 0 && rtcb->irqcount > 0);
-      DEBUGASSERT(rtcb->irqcount > 0);
 
       /* Will we still have interrupts disabled after decrementing the
        * count?
@@ -211,5 +237,25 @@ void leave_critical_section(irqstate_t flags)
       up_irq_restore(flags);
     }
 }
+#else /* defined(CONFIG_SCHED_INSTRUMENTATION_CSECTION) */
+void leave_critical_section(irqstate_t flags)
+{
+  /* Check if we were called from an interrupt handler */
 
-#endif /* CONFIG_SMP */
+  if (!up_interrupt_context())
+    {
+      FAR struct tcb_s *rtcb = this_task();
+      DEBUGASSERT(rtcb != NULL);
+
+      /* Note that we have left the critical section */
+
+      sched_note_csection(rtcb, false);
+    }
+
+  /* Restore the previous interrupt state. */
+
+  up_irq_restore(flags);
+}
+#endif
+
+#endif /* CONFIG_SMP || CONFIG_SCHED_INSTRUMENTATION_CSECTION*/

sched/sched/sched_note.c

@@ -401,8 +401,6 @@ void sched_note_csection(FAR struct tcb_s *tcb, bool enter)
   note.ncs_count[1] = (uint8_t)((tcb->irqcount >> 8) & 0xff);
 #endif
 
-  note_systime((FAR struct note_common_s *)&note);
-
   /* Add the note to circular buffer */
 
   note_add((FAR const uint8_t *)&note, sizeof(struct note_csection_s));
@@ -450,7 +448,7 @@ ssize_t sched_note_get(FAR uint8_t *buffer, size_t buflen)
 
   /* Get the index to the tail of the circular buffer */
 
-  tail = g_note_info.ni_tail;
+  tail    = g_note_info.ni_tail;
   DEBUGASSERT(tail < CONFIG_SCHED_NOTE_BUFSIZE);
 
   /* Get the length of the note at the tail index */
@@ -467,7 +465,7 @@ ssize_t sched_note_get(FAR uint8_t *buffer, size_t buflen)
 
       note_remove();
 
-      /* and return and error */
+      /* and return an error */
 
       notelen = -EFBIG;
       goto errout_with_csection;