[PATCH v3 15/17] rv: Replace tss monitor with more complete sts

@@ -40,26 +40,6 @@ defined in by Daniel Bristot in [1].
 
 Currently we included the following:
 
-Monitor tss
-~~~~~~~~~~~
-
-The task switch while scheduling (tss) monitor ensures a task switch happens
-only in scheduling context, that is inside a call to `__schedule`::
-
-                     |
-                     |
-                     v
-                   +-----------------+
-                   |     thread      | <+
-                   +-----------------+  |
-                     |                  |
-                     | schedule_entry   | schedule_exit
-                     v                  |
-    sched_switch                        |
-  +---------------                      |
-  |                       sched         |
-  +-------------->                     -+
-
 Monitor sco
 ~~~~~~~~~~~
 

@@ -170,6 +150,54 @@ schedule is not called with interrupt disabled::
                                        |
                         cant_sched    -+
 
+Monitor sts
+~~~~~~~~~~~
+
+The schedule implies task switch (sts) monitor ensures a task switch happens in
+every scheduling context, that is inside a call to ``__schedule``, as well as no
+task switch can happen without scheduling and before interrupts are disabled.
+This require the special type of switch called vain, which occurs when the next
+task picked for execution is the same as the previously running one, in fact no
+real task switch occurs::
+
+                    |
+                    |
+                    v
+                  #====================#   irq_disable
+                  H                    H   irq_enable
+                  H       thread       H --------------+
+                  H                    H               |
+  +-------------> H                    H <-------------+
+  |               #====================#
+  |                 |
+  |                 | schedule_entry
+  |                 v
+  |               +--------------------+
+  |               |     scheduling     | <+
+  |               +--------------------+  |
+  |                 |                     |
+  |                 | irq_disable         | irq_enable
+  |                 v                     |
+  |               +--------------------+  |
+  |               | disable_to_switch  | -+
+  | schedule_exit +--------------------+
+  |                 |
+  |                 | sched_switch
+  |                 | sched_switch_vain
+  |                 v
+  |               +--------------------+
+  |               |     switching      |
+  |               +--------------------+
+  |                 |
+  |                 | irq_enable
+  |                 v
+  |               +--------------------+   irq_disable
+  |               |                    |   irq_enable
+  |               |   enable_to_exit   | --------------+
+  |               |                    |               |
+  +-------------- |                    | <-------------+
+                  +--------------------+
+
 References
 ----------
 

@@ -45,12 +45,12 @@ source "kernel/trace/rv/monitors/wip/Kconfig"
 source "kernel/trace/rv/monitors/wwnr/Kconfig"
 
 source "kernel/trace/rv/monitors/sched/Kconfig"
-source "kernel/trace/rv/monitors/tss/Kconfig"
 source "kernel/trace/rv/monitors/sco/Kconfig"
 source "kernel/trace/rv/monitors/snroc/Kconfig"
 source "kernel/trace/rv/monitors/scpd/Kconfig"
 source "kernel/trace/rv/monitors/snep/Kconfig"
 source "kernel/trace/rv/monitors/sncid/Kconfig"
+source "kernel/trace/rv/monitors/sts/Kconfig"
 # Add new sched monitors here
 
 source "kernel/trace/rv/monitors/rtapp/Kconfig"

@@ -6,7 +6,6 @@ obj-$(CONFIG_RV) += rv.o
 obj-$(CONFIG_RV_MON_WIP) += monitors/wip/wip.o
 obj-$(CONFIG_RV_MON_WWNR) += monitors/wwnr/wwnr.o
 obj-$(CONFIG_RV_MON_SCHED) += monitors/sched/sched.o
-obj-$(CONFIG_RV_MON_TSS) += monitors/tss/tss.o
 obj-$(CONFIG_RV_MON_SCO) += monitors/sco/sco.o
 obj-$(CONFIG_RV_MON_SNROC) += monitors/snroc/snroc.o
 obj-$(CONFIG_RV_MON_SCPD) += monitors/scpd/scpd.o

@@ -15,6 +14,7 @@ obj-$(CONFIG_RV_MON_SNCID) += monitors/sncid/sncid.o
 obj-$(CONFIG_RV_MON_RTAPP) += monitors/rtapp/rtapp.o
 obj-$(CONFIG_RV_MON_PAGEFAULT) += monitors/pagefault/pagefault.o
 obj-$(CONFIG_RV_MON_SLEEP) += monitors/sleep/sleep.o
+obj-$(CONFIG_RV_MON_STS) += monitors/sts/sts.o
 # Add new monitors here
 obj-$(CONFIG_RV_REACTORS) += rv_reactors.o
 obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o

@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+config RV_MON_STS
+	depends on RV
+	depends on TRACE_IRQFLAGS
+	depends on RV_MON_SCHED
+	default y
+	select DA_MON_EVENTS_IMPLICIT
+	bool "sts monitor"
+	help
+	  Monitor to ensure relationships between scheduler and switches
+	   * each call to the scheduler implies a switch
+	   * switches only happen inside the scheduler
+	   * switches happen with interrupt disabled
+	  This monitor is part of the sched monitors collection.
+
+	  For further information, see:
+	    Documentation/trace/rv/monitor_sched.rst

@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ftrace.h>
+#include <linux/tracepoint.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rv.h>
+#include <rv/instrumentation.h>
+#include <rv/da_monitor.h>
+
+#define MODULE_NAME "sts"
+
+#include <trace/events/sched.h>
+#include <trace/events/preemptirq.h>
+#include <rv_trace.h>
+#include <monitors/sched/sched.h>
+
+#include "sts.h"
+
+static struct rv_monitor rv_sts;
+DECLARE_DA_MON_PER_CPU(sts, unsigned char);
+
+static void handle_irq_disable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+	da_handle_event_sts(irq_disable_sts);
+}
+
+static void handle_irq_enable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+	da_handle_event_sts(irq_enable_sts);
+}
+
+static void handle_sched_switch(void *data, bool preempt,
+				struct task_struct *prev,
+				struct task_struct *next,
+				unsigned int prev_state)
+{
+	da_handle_event_sts(sched_switch_sts);
+}
+
+static void handle_sched_switch_vain(void *data, bool preempt,
+				     struct task_struct *tsk,
+				     unsigned int tsk_state)
+{
+	da_handle_event_sts(sched_switch_vain_sts);
+}
+
+static void handle_schedule_entry(void *data, bool preempt, unsigned long ip)
+{
+	da_handle_event_sts(schedule_entry_sts);
+}
+
+static void handle_schedule_exit(void *data, bool is_switch, unsigned long ip)
+{
+	da_handle_start_event_sts(schedule_exit_sts);
+}
+
+static int enable_sts(void)
+{
+	int retval;
+
+	retval = da_monitor_init_sts();
+	if (retval)
+		return retval;
+
+	rv_attach_trace_probe("sts", irq_disable, handle_irq_disable);
+	rv_attach_trace_probe("sts", irq_enable, handle_irq_enable);
+	rv_attach_trace_probe("sts", sched_switch, handle_sched_switch);
+	rv_attach_trace_probe("sts", sched_switch_vain_tp, handle_sched_switch_vain);
+	rv_attach_trace_probe("sts", sched_entry_tp, handle_schedule_entry);
+	rv_attach_trace_probe("sts", sched_exit_tp, handle_schedule_exit);
+
+	return 0;
+}
+
+static void disable_sts(void)
+{
+	rv_sts.enabled = 0;
+
+	rv_detach_trace_probe("sts", irq_disable, handle_irq_disable);
+	rv_detach_trace_probe("sts", irq_enable, handle_irq_enable);
+	rv_detach_trace_probe("sts", sched_switch, handle_sched_switch);
+	rv_detach_trace_probe("sts", sched_switch_vain_tp, handle_sched_switch_vain);
+	rv_detach_trace_probe("sts", sched_entry_tp, handle_schedule_entry);
+	rv_detach_trace_probe("sts", sched_exit_tp, handle_schedule_exit);
+
+	da_monitor_destroy_sts();
+}
+
+/*
+ * This is the monitor register section.
+ */
+static struct rv_monitor rv_sts = {
+	.name = "sts",
+	.description = "schedule implies task switch.",
+	.enable = enable_sts,
+	.disable = disable_sts,
+	.reset = da_monitor_reset_all_sts,
+	.enabled = 0,
+};
+
+static int __init register_sts(void)
+{
+	return rv_register_monitor(&rv_sts, &rv_sched);
+}
+
+static void __exit unregister_sts(void)
+{
+	rv_unregister_monitor(&rv_sts);
+}
+
+module_init(register_sts);
+module_exit(unregister_sts);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
+MODULE_DESCRIPTION("sts: schedule implies task switch.");

@@ -0,0 +1,97 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Automatically generated C representation of sts automaton
+ * For further information about this format, see kernel documentation:
+ *   Documentation/trace/rv/deterministic_automata.rst
+ */
+
+enum states_sts {
+	thread_sts = 0,
+	disable_to_switch_sts,
+	enable_to_exit_sts,
+	scheduling_sts,
+	switching_sts,
+	state_max_sts
+};
+
+#define INVALID_STATE state_max_sts
+
+enum events_sts {
+	irq_disable_sts = 0,
+	irq_enable_sts,
+	sched_switch_sts,
+	sched_switch_vain_sts,
+	schedule_entry_sts,
+	schedule_exit_sts,
+	event_max_sts
+};
+
+struct automaton_sts {
+	char *state_names[state_max_sts];
+	char *event_names[event_max_sts];
+	unsigned char function[state_max_sts][event_max_sts];
+	unsigned char initial_state;
+	bool final_states[state_max_sts];
+};
+
+static const struct automaton_sts automaton_sts = {
+	.state_names = {
+		"thread",
+		"disable_to_switch",
+		"enable_to_exit",
+		"scheduling",
+		"switching"
+	},
+	.event_names = {
+		"irq_disable",
+		"irq_enable",
+		"sched_switch",
+		"sched_switch_vain",
+		"schedule_entry",
+		"schedule_exit"
+	},
+	.function = {
+		{
+			thread_sts,
+			thread_sts,
+			INVALID_STATE,
+			INVALID_STATE,
+			scheduling_sts,
+			INVALID_STATE
+		},
+		{
+			INVALID_STATE,
+			scheduling_sts,
+			switching_sts,
+			switching_sts,
+			INVALID_STATE,
+			INVALID_STATE
+		},
+		{
+			enable_to_exit_sts,
+			enable_to_exit_sts,
+			INVALID_STATE,
+			INVALID_STATE,
+			INVALID_STATE,
+			thread_sts
+		},
+		{
+			disable_to_switch_sts,
+			INVALID_STATE,
+			INVALID_STATE,
+			INVALID_STATE,
+			INVALID_STATE,
+			INVALID_STATE
+		},
+		{
+			INVALID_STATE,
+			enable_to_exit_sts,
+			INVALID_STATE,
+			INVALID_STATE,
+			INVALID_STATE,
+			INVALID_STATE
+		},
+	},
+	.initial_state = thread_sts,
+	.final_states = { 1, 0, 0, 0, 0 },
+};

@@ -4,12 +4,12 @@
  * Snippet to be included in rv_trace.h
  */
 
-#ifdef CONFIG_RV_MON_TSS
-DEFINE_EVENT(event_da_monitor, event_tss,
+#ifdef CONFIG_RV_MON_STS
+DEFINE_EVENT(event_da_monitor, event_sts,
 	     TP_PROTO(char *state, char *event, char *next_state, bool final_state),
 	     TP_ARGS(state, event, next_state, final_state));
 
-DEFINE_EVENT(error_da_monitor, error_tss,
+DEFINE_EVENT(error_da_monitor, error_sts,
 	     TP_PROTO(char *state, char *event),
 	     TP_ARGS(state, event));
-#endif /* CONFIG_RV_MON_TSS */
+#endif /* CONFIG_RV_MON_STS */

@@ -1,14 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0-only
-#
-config RV_MON_TSS
-	depends on RV
-	depends on RV_MON_SCHED
-	default y
-	select DA_MON_EVENTS_IMPLICIT
-	bool "tss monitor"
-	help
-	  Monitor to ensure sched_switch happens only in scheduling context.
-	  This monitor is part of the sched monitors collection.
-
-	  For further information, see:
-	    Documentation/trace/rv/monitor_sched.rst

@@ -1,90 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <linux/ftrace.h>
-#include <linux/tracepoint.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/rv.h>
-#include <rv/instrumentation.h>
-#include <rv/da_monitor.h>
-
-#define MODULE_NAME "tss"
-
-#include <trace/events/sched.h>
-#include <rv_trace.h>
-#include <monitors/sched/sched.h>
-
-#include "tss.h"
-
-static struct rv_monitor rv_tss;
-DECLARE_DA_MON_PER_CPU(tss, unsigned char);
-
-static void handle_sched_switch(void *data, bool preempt,
-				struct task_struct *prev,
-				struct task_struct *next,
-				unsigned int prev_state)
-{
-	da_handle_event_tss(sched_switch_tss);
-}
-
-static void handle_schedule_entry(void *data, bool preempt, unsigned long ip)
-{
-	da_handle_event_tss(schedule_entry_tss);
-}
-
-static void handle_schedule_exit(void *data, bool is_switch, unsigned long ip)
-{
-	da_handle_start_event_tss(schedule_exit_tss);
-}
-
-static int enable_tss(void)
-{
-	int retval;
-
-	retval = da_monitor_init_tss();
-	if (retval)
-		return retval;
-
-	rv_attach_trace_probe("tss", sched_switch, handle_sched_switch);
-	rv_attach_trace_probe("tss", sched_entry_tp, handle_schedule_entry);
-	rv_attach_trace_probe("tss", sched_exit_tp, handle_schedule_exit);
-
-	return 0;
-}
-
-static void disable_tss(void)
-{
-	rv_tss.enabled = 0;
-
-	rv_detach_trace_probe("tss", sched_switch, handle_sched_switch);
-	rv_detach_trace_probe("tss", sched_entry_tp, handle_schedule_entry);
-	rv_detach_trace_probe("tss", sched_exit_tp, handle_schedule_exit);
-
-	da_monitor_destroy_tss();
-}
-
-static struct rv_monitor rv_tss = {
-	.name = "tss",
-	.description = "task switch while scheduling.",
-	.enable = enable_tss,
-	.disable = disable_tss,
-	.reset = da_monitor_reset_all_tss,
-	.enabled = 0,
-};
-
-static int __init register_tss(void)
-{
-	return rv_register_monitor(&rv_tss, &rv_sched);
-}
-
-static void __exit unregister_tss(void)
-{
-	rv_unregister_monitor(&rv_tss);
-}
-
-module_init(register_tss);
-module_exit(unregister_tss);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
-MODULE_DESCRIPTION("tss: task switch while scheduling.");

@@ -1,47 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Automatically generated C representation of tss automaton
- * For further information about this format, see kernel documentation:
- *   Documentation/trace/rv/deterministic_automata.rst
- */
-
-enum states_tss {
-	thread_tss = 0,
-	sched_tss,
-	state_max_tss
-};
-
-#define INVALID_STATE state_max_tss
-
-enum events_tss {
-	sched_switch_tss = 0,
-	schedule_entry_tss,
-	schedule_exit_tss,
-	event_max_tss
-};
-
-struct automaton_tss {
-	char *state_names[state_max_tss];
-	char *event_names[event_max_tss];
-	unsigned char function[state_max_tss][event_max_tss];
-	unsigned char initial_state;
-	bool final_states[state_max_tss];
-};
-
-static const struct automaton_tss automaton_tss = {
-	.state_names = {
-		"thread",
-		"sched"
-	},
-	.event_names = {
-		"sched_switch",
-		"schedule_entry",
-		"schedule_exit"
-	},
-	.function = {
-		{     INVALID_STATE,         sched_tss,     INVALID_STATE },
-		{         sched_tss,     INVALID_STATE,        thread_tss },
-	},
-	.initial_state = thread_tss,
-	.final_states = { 1, 0 },
-};

@@ -58,11 +58,11 @@ DECLARE_EVENT_CLASS(error_da_monitor,
 );
 
 #include <monitors/wip/wip_trace.h>
-#include <monitors/tss/tss_trace.h>
 #include <monitors/sco/sco_trace.h>
 #include <monitors/scpd/scpd_trace.h>
 #include <monitors/snep/snep_trace.h>
 #include <monitors/sncid/sncid_trace.h>
+#include <monitors/sts/sts_trace.h>
 // Add new monitors based on CONFIG_DA_MON_EVENTS_IMPLICIT here
 
 #endif /* CONFIG_DA_MON_EVENTS_IMPLICIT */

@@ -0,0 +1,29 @@
+digraph state_automaton {
+	center = true;
+	size = "7,11";
+	{node [shape = circle] "disable_to_switch"};
+	{node [shape = circle] "enable_to_exit"};
+	{node [shape = circle] "scheduling"};
+	{node [shape = circle] "switching"};
+	{node [shape = plaintext, style=invis, label=""] "__init_thread"};
+	{node [shape = doublecircle] "thread"};
+	{node [shape = circle] "thread"};
+	"__init_thread" -> "thread";
+	"disable_to_switch" [label = "disable_to_switch"];
+	"disable_to_switch" -> "scheduling" [ label = "irq_enable" ];
+	"disable_to_switch" -> "switching" [ label = "sched_switch\nsched_switch_vain" ];
+	"enable_to_exit" [label = "enable_to_exit"];
+	"enable_to_exit" -> "enable_to_exit" [ label = "irq_disable\nirq_enable" ];
+	"enable_to_exit" -> "thread" [ label = "schedule_exit" ];
+	"scheduling" [label = "scheduling"];
+	"scheduling" -> "disable_to_switch" [ label = "irq_disable" ];
+	"switching" [label = "switching"];
+	"switching" -> "enable_to_exit" [ label = "irq_enable" ];
+	"thread" [label = "thread", color = green3];
+	"thread" -> "scheduling" [ label = "schedule_entry" ];
+	"thread" -> "thread" [ label = "irq_disable\nirq_enable" ];
+	{ rank = min ;
+		"__init_thread";
+		"thread";
+	}
+}

@@ -1,18 +0,0 @@
-digraph state_automaton {
-	center = true;
-	size = "7,11";
-	{node [shape = plaintext] "sched"};
-	{node [shape = plaintext, style=invis, label=""] "__init_thread"};
-	{node [shape = ellipse] "thread"};
-	{node [shape = plaintext] "thread"};
-	"__init_thread" -> "thread";
-	"sched" [label = "sched"];
-	"sched" -> "sched" [ label = "sched_switch" ];
-	"sched" -> "thread" [ label = "schedule_exit" ];
-	"thread" [label = "thread", color = green3];
-	"thread" -> "sched" [ label = "schedule_entry" ];
-	{ rank = min ;
-		"__init_thread";
-		"thread";
-	}
-}