[PATCH 0/2] Tests for preempt/irq disabled sections

[PATCH 0/2] Tests for preempt/irq disabled sections

[Joel Fernandes]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

Only resending the test module and kselftest patches with minor changes
as suggested by Steve.

Previous posting of the series is at: https://lkml.org/lkml/2018/6/7/1162

Joel Fernandes (Google) (2):
  lib: Add module for testing preemptoff/irqsoff latency tracers
  kselftests: Add tests for the preemptoff and irqsoff tracers

 kernel/trace/Kconfig                          | 15 ++++
 kernel/trace/Makefile                         |  1 +
 kernel/trace/preemptirq_delay_test.c          | 72 ++++++++++++++++++
 tools/testing/selftests/ftrace/config         |  3 +
 .../test.d/preemptirq/irqsoff_tracer.tc       | 73 +++++++++++++++++++
 5 files changed, 164 insertions(+)
 create mode 100644 kernel/trace/preemptirq_delay_test.c
 create mode 100644 tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc

-- 
2.18.0.203.gfac676dfb9-goog
unction incase tracepoints aren't enabled, did that.

[PATCH 1/2] lib: Add module for testing preemptoff/irqsoff latency tracers

[Joel Fernandes]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

Here we introduce a test module for introducing a long preempt or irq
disable delay in the kernel which the preemptoff or irqsoff tracers can
detect. This module is to be used only for test purposes and is default
disabled.

Following is the expected output (only briefly shown) that can be parsed
to verify that the tracers are working correctly. We will use this from
the kselftests in future patches.

For the preemptoff tracer:

echo preemptoff > /d/tracing/current_tracer
sleep 1
insmod ./preemptirq_delay_test.ko test_mode=preempt delay=500000
sleep 1
bash-4.3# cat /d/tracing/trace
preempt -1066    2...2    0us@: preemptirq_delay_run <-preemptirq_delay_run
preempt -1066    2...2 500002us : preemptirq_delay_run <-preemptirq_delay_run
preempt -1066    2...2 500004us : tracer_preempt_on <-preemptirq_delay_run
preempt -1066    2...2 500012us : <stack trace>
 => kthread
 => ret_from_fork

For the irqsoff tracer:

echo irqsoff > /d/tracing/current_tracer
sleep 1
insmod ./preemptirq_delay_test.ko test_mode=irq delay=500000
sleep 1
bash-4.3# cat /d/tracing/trace
irq dis -1069    1d..1    0us@: preemptirq_delay_run
irq dis -1069    1d..1 500001us : preemptirq_delay_run
irq dis -1069    1d..1 500002us : tracer_hardirqs_on <-preemptirq_delay_run
irq dis -1069    1d..1 500005us : <stack trace>
 => ret_from_fork

Co-developed-by: Erick Reyes <erickreyes@google.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 kernel/trace/Kconfig                 | 15 ++++++
 kernel/trace/Makefile                |  1 +
 kernel/trace/preemptirq_delay_test.c | 72 ++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+)
 create mode 100644 kernel/trace/preemptirq_delay_test.c

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 8d51351e3149..eb5ab6b511e2 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -699,6 +699,21 @@ config RING_BUFFER_STARTUP_TEST
 
 	 If unsure, say N
 
+config PREEMPTIRQ_DELAY_TEST
+	tristate "Preempt / IRQ disable delay thread to test latency tracers"
+	depends on m
+	help
+	  Select this option to build a test module that can help test latency
+	  tracers by executing a preempt or irq disable section with a user
+	  configurable delay. The module busy waits for the duration of the
+	  critical section.
+
+	  For example, the following invocation forces a one-time irq-disabled
+	  critical section for 500us:
+	  modprobe preemptirq_delay_test test_mode=irq delay=500000
+
+	  If unsure, say N
+
 config TRACE_EVAL_MAP_FILE
        bool "Show eval mappings for trace events"
        depends on TRACING
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 84a0cb222f20..677540bb1b62 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_TRACING_MAP) += tracing_map.o
 obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
 obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
 obj-$(CONFIG_PREEMPTIRQ_TRACEPOINTS) += trace_preemptirq.o
+obj-$(CONFIG_PREEMPTIRQ_DELAY_TEST) += preemptirq_delay_test.o
 obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
 obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
 obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq_delay_test.c
new file mode 100644
index 000000000000..c97a026c0720
--- /dev/null
+++ b/kernel/trace/preemptirq_delay_test.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Preempt / IRQ disable delay thread to test latency tracers
+ *
+ * Copyright (C) 2018 Joel Fernandes (Google) <joel@joelfernandes.org>
+ */
+
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/string.h>
+
+static ulong delay = 100;
+static char test_mode[10] = "irq";
+
+module_param_named(delay, delay, ulong, S_IRUGO);
+module_param_string(test_mode, test_mode, 10, S_IRUGO);
+MODULE_PARM_DESC(delay, "Period in microseconds (100 uS default)");
+MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt or irq (default irq)");
+
+static void busy_wait(ulong time)
+{
+	ktime_t start, end;
+	start = ktime_get();
+	do {
+		end = ktime_get();
+		if (kthread_should_stop())
+			break;
+	} while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000));
+}
+
+int preemptirq_delay_run(void *data)
+{
+	unsigned long flags;
+
+	if (!strcmp(test_mode, "irq")) {
+		local_irq_save(flags);
+		busy_wait(delay);
+		local_irq_restore(flags);
+	} else if (!strcmp(test_mode, "preempt")) {
+		preempt_disable();
+		busy_wait(delay);
+		preempt_enable();
+	}
+
+	return 0;
+}
+
+static int __init preemptirq_delay_init(void)
+{
+	char task_name[50];
+	struct task_struct *test_task;
+
+	snprintf(task_name, sizeof(task_name), "%s_test", test_mode);
+
+	test_task = kthread_run(preemptirq_delay_run, NULL, task_name);
+	return PTR_ERR_OR_ZERO(test_task);
+}
+
+static void __exit preemptirq_delay_exit(void)
+{
+	return;
+}
+
+module_init(preemptirq_delay_init)
+module_exit(preemptirq_delay_exit)
+MODULE_LICENSE("GPL v2");
-- 
2.18.0.203.gfac676dfb9-goog

Re: [PATCH 1/2] lib: Add module for testing preemptoff/irqsoff latency tracers

[Steven Rostedt]

On Tue, 10 Jul 2018 23:35:39 -0700
Joel Fernandes <joel@joelfernandes.org> wrote:

> 
> Co-developed-by: Erick Reyes <erickreyes@google.com>

A co-developer needs to add their signed off by. To specify that Erick
is a co-author, you could do:

[ Erick is a co-developer of this commit ]
Signed-off-by: Add Erick's SOB here.

> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> ---
>  kernel/trace/Kconfig                 | 15 ++++++
>  kernel/trace/Makefile                |  1 +
>  kernel/trace/preemptirq_delay_test.c | 72 ++++++++++++++++++++++++++++
>  3 files changed, 88 insertions(+)
>  create mode 100644 kernel/trace/preemptirq_delay_test.c
> 
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 8d51351e3149..eb5ab6b511e2 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -699,6 +699,21 @@ config RING_BUFFER_STARTUP_TEST
>  
>  	 If unsure, say N
>  
> +config PREEMPTIRQ_DELAY_TEST
> +	tristate "Preempt / IRQ disable delay thread to test latency tracers"
> +	depends on m
> +	help
> +	  Select this option to build a test module that can help test latency
> +	  tracers by executing a preempt or irq disable section with a user
> +	  configurable delay. The module busy waits for the duration of the
> +	  critical section.
> +
> +	  For example, the following invocation forces a one-time irq-disabled
> +	  critical section for 500us:
> +	  modprobe preemptirq_delay_test test_mode=irq delay=500000
> +
> +	  If unsure, say N
> +
>  config TRACE_EVAL_MAP_FILE
>         bool "Show eval mappings for trace events"
>         depends on TRACING
> diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> index 84a0cb222f20..677540bb1b62 100644
> --- a/kernel/trace/Makefile
> +++ b/kernel/trace/Makefile
> @@ -36,6 +36,7 @@ obj-$(CONFIG_TRACING_MAP) += tracing_map.o
>  obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
>  obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
>  obj-$(CONFIG_PREEMPTIRQ_TRACEPOINTS) += trace_preemptirq.o
> +obj-$(CONFIG_PREEMPTIRQ_DELAY_TEST) += preemptirq_delay_test.o
>  obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
>  obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
>  obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
> diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq_delay_test.c
> new file mode 100644
> index 000000000000..c97a026c0720
> --- /dev/null
> +++ b/kernel/trace/preemptirq_delay_test.c
> @@ -0,0 +1,72 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Preempt / IRQ disable delay thread to test latency tracers
> + *
> + * Copyright (C) 2018 Joel Fernandes (Google) <joel@joelfernandes.org>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/kernel.h>
> +#include <linux/kthread.h>
> +#include <linux/ktime.h>
> +#include <linux/module.h>
> +#include <linux/printk.h>
> +#include <linux/string.h>
> +
> +static ulong delay = 100;
> +static char test_mode[10] = "irq";
> +
> +module_param_named(delay, delay, ulong, S_IRUGO);
> +module_param_string(test_mode, test_mode, 10, S_IRUGO);
> +MODULE_PARM_DESC(delay, "Period in microseconds (100 uS default)");
> +MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt or irq (default irq)");
> +
> +static void busy_wait(ulong time)
> +{
> +	ktime_t start, end;
> +	start = ktime_get();
> +	do {
> +		end = ktime_get();
> +		if (kthread_should_stop())
> +			break;
> +	} while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000));
> +}
> +
> +int preemptirq_delay_run(void *data)
> +{
> +	unsigned long flags;
> +
> +	if (!strcmp(test_mode, "irq")) {
> +		local_irq_save(flags);
> +		busy_wait(delay);
> +		local_irq_restore(flags);
> +	} else if (!strcmp(test_mode, "preempt")) {
> +		preempt_disable();
> +		busy_wait(delay);
> +		preempt_enable();
> +	}
> +
> +	return 0;
> +}
> +
> +static int __init preemptirq_delay_init(void)
> +{
> +	char task_name[50];
> +	struct task_struct *test_task;
> +
> +	snprintf(task_name, sizeof(task_name), "%s_test", test_mode);
> +
> +	test_task = kthread_run(preemptirq_delay_run, NULL, task_name);
> +	return PTR_ERR_OR_ZERO(test_task);
> +}
> +
> +static void __exit preemptirq_delay_exit(void)
> +{
> +	return;
> +}
> +
> +module_init(preemptirq_delay_init)
> +module_exit(preemptirq_delay_exit)
> +MODULE_LICENSE("GPL v2");

Re: [PATCH 1/2] lib: Add module for testing preemptoff/irqsoff latency tracers

[Joel Fernandes]

On Thu, Jul 12, 2018 at 05:22:32PM -0400, Steven Rostedt wrote:
> On Tue, 10 Jul 2018 23:35:39 -0700
> Joel Fernandes <joel@joelfernandes.org> wrote:
> 
> > 
> > Co-developed-by: Erick Reyes <erickreyes@google.com>
> 
> A co-developer needs to add their signed off by. To specify that Erick
> is a co-author, you could do:
> 
> [ Erick is a co-developer of this commit ]
> Signed-off-by: Add Erick's SOB here.

Sure, I added this below. Hope its easy for you to apply, if not let me know
and I can send it again separately. thanks.

------------>8----------------

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Subject: [PATCH 1/2] lib: Add module for testing preemptoff/irqsoff latency  tracers

Here we introduce a test module for introducing a long preempt or irq
disable delay in the kernel which the preemptoff or irqsoff tracers can
detect. This module is to be used only for test purposes and is default
disabled.

Following is the expected output (only briefly shown) that can be parsed
to verify that the tracers are working correctly. We will use this from
the kselftests in future patches.

For the preemptoff tracer:

echo preemptoff > /d/tracing/current_tracer
sleep 1
insmod ./preemptirq_delay_test.ko test_mode=preempt delay=500000
sleep 1
bash-4.3# cat /d/tracing/trace
preempt -1066    2...2    0us@: preemptirq_delay_run <-preemptirq_delay_run
preempt -1066    2...2 500002us : preemptirq_delay_run <-preemptirq_delay_run
preempt -1066    2...2 500004us : tracer_preempt_on <-preemptirq_delay_run
preempt -1066    2...2 500012us : <stack trace>
 => kthread
 => ret_from_fork

For the irqsoff tracer:

echo irqsoff > /d/tracing/current_tracer
sleep 1
insmod ./preemptirq_delay_test.ko test_mode=irq delay=500000
sleep 1
bash-4.3# cat /d/tracing/trace
irq dis -1069    1d..1    0us@: preemptirq_delay_run
irq dis -1069    1d..1 500001us : preemptirq_delay_run
irq dis -1069    1d..1 500002us : tracer_hardirqs_on <-preemptirq_delay_run
irq dis -1069    1d..1 500005us : <stack trace>
 => ret_from_fork

Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[ Erick is a co-developer of this commit ]
Signed-off-by: Erick Reyes <erickreyes@google.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 kernel/trace/Kconfig                 | 15 ++++++
 kernel/trace/Makefile                |  1 +
 kernel/trace/preemptirq_delay_test.c | 72 ++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+)
 create mode 100644 kernel/trace/preemptirq_delay_test.c

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 8d51351e3149..eb5ab6b511e2 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -699,6 +699,21 @@ config RING_BUFFER_STARTUP_TEST
 
 	 If unsure, say N
 
+config PREEMPTIRQ_DELAY_TEST
+	tristate "Preempt / IRQ disable delay thread to test latency tracers"
+	depends on m
+	help
+	  Select this option to build a test module that can help test latency
+	  tracers by executing a preempt or irq disable section with a user
+	  configurable delay. The module busy waits for the duration of the
+	  critical section.
+
+	  For example, the following invocation forces a one-time irq-disabled
+	  critical section for 500us:
+	  modprobe preemptirq_delay_test test_mode=irq delay=500000
+
+	  If unsure, say N
+
 config TRACE_EVAL_MAP_FILE
        bool "Show eval mappings for trace events"
        depends on TRACING
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 84a0cb222f20..677540bb1b62 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_TRACING_MAP) += tracing_map.o
 obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
 obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
 obj-$(CONFIG_PREEMPTIRQ_TRACEPOINTS) += trace_preemptirq.o
+obj-$(CONFIG_PREEMPTIRQ_DELAY_TEST) += preemptirq_delay_test.o
 obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
 obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
 obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq_delay_test.c
new file mode 100644
index 000000000000..c97a026c0720
--- /dev/null
+++ b/kernel/trace/preemptirq_delay_test.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Preempt / IRQ disable delay thread to test latency tracers
+ *
+ * Copyright (C) 2018 Joel Fernandes (Google) <joel@joelfernandes.org>
+ */
+
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/string.h>
+
+static ulong delay = 100;
+static char test_mode[10] = "irq";
+
+module_param_named(delay, delay, ulong, S_IRUGO);
+module_param_string(test_mode, test_mode, 10, S_IRUGO);
+MODULE_PARM_DESC(delay, "Period in microseconds (100 uS default)");
+MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt or irq (default irq)");
+
+static void busy_wait(ulong time)
+{
+	ktime_t start, end;
+	start = ktime_get();
+	do {
+		end = ktime_get();
+		if (kthread_should_stop())
+			break;
+	} while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000));
+}
+
+int preemptirq_delay_run(void *data)
+{
+	unsigned long flags;
+
+	if (!strcmp(test_mode, "irq")) {
+		local_irq_save(flags);
+		busy_wait(delay);
+		local_irq_restore(flags);
+	} else if (!strcmp(test_mode, "preempt")) {
+		preempt_disable();
+		busy_wait(delay);
+		preempt_enable();
+	}
+
+	return 0;
+}
+
+static int __init preemptirq_delay_init(void)
+{
+	char task_name[50];
+	struct task_struct *test_task;
+
+	snprintf(task_name, sizeof(task_name), "%s_test", test_mode);
+
+	test_task = kthread_run(preemptirq_delay_run, NULL, task_name);
+	return PTR_ERR_OR_ZERO(test_task);
+}
+
+static void __exit preemptirq_delay_exit(void)
+{
+	return;
+}
+
+module_init(preemptirq_delay_init)
+module_exit(preemptirq_delay_exit)
+MODULE_LICENSE("GPL v2");
-- 
2.18.0.203.gfac676dfb9-goog

Re: [PATCH 1/2] lib: Add module for testing preemptoff/irqsoff latency tracers

[Steven Rostedt]

On Thu, 12 Jul 2018 14:36:11 -0700
Joel Fernandes <joel@joelfernandes.org> wrote:

> Sure, I added this below. Hope its easy for you to apply, if not let me know
> and I can send it again separately. thanks.

Thanks, I added this in my queue.

-- Steve

[PATCH 2/2] kselftests: Add tests for the preemptoff and irqsoff tracers

[Joel Fernandes]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

Here we add unit tests for the preemptoff and irqsoff tracer by using a
kernel module introduced previously to trigger long preempt or irq
disabled sections in the kernel.

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 tools/testing/selftests/ftrace/config         |  3 +
 .../test.d/preemptirq/irqsoff_tracer.tc       | 73 +++++++++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc

diff --git a/tools/testing/selftests/ftrace/config b/tools/testing/selftests/ftrace/config
index b01924c71c09..07db5ab09cc7 100644
--- a/tools/testing/selftests/ftrace/config
+++ b/tools/testing/selftests/ftrace/config
@@ -4,3 +4,6 @@ CONFIG_FUNCTION_PROFILER=y
 CONFIG_TRACER_SNAPSHOT=y
 CONFIG_STACK_TRACER=y
 CONFIG_HIST_TRIGGERS=y
+CONFIG_PREEMPT_TRACER=y
+CONFIG_IRQSOFF_TRACER=y
+CONFIG_PREEMPTIRQ_DELAY_TEST=m
diff --git a/tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc b/tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc
new file mode 100644
index 000000000000..cbd174334a48
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc
@@ -0,0 +1,73 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: test for the preemptirqsoff tracer
+
+MOD=preemptirq_delay_test
+
+fail() {
+    reset_tracer
+    rmmod $MOD || true
+    exit_fail
+}
+
+unsup() { #msg
+    reset_tracer
+    rmmod $MOD || true
+    echo $1
+    exit_unsupported
+}
+
+modprobe $MOD || unsup "$MOD module not available"
+rmmod $MOD
+
+grep -q "preemptoff" available_tracers || unsup "preemptoff tracer not enabled"
+grep -q "irqsoff" available_tracers || unsup "irqsoff tracer not enabled"
+
+reset_tracer
+
+# Simulate preemptoff section for half a second couple of times
+echo preemptoff > current_tracer
+sleep 1
+modprobe $MOD test_mode=preempt delay=500000 || fail
+rmmod $MOD || fail
+modprobe $MOD test_mode=preempt delay=500000 || fail
+rmmod $MOD || fail
+modprobe $MOD test_mode=preempt delay=500000 || fail
+rmmod $MOD || fail
+
+cat trace
+
+# Confirm which tracer
+grep -q "tracer: preemptoff" trace || fail
+
+# Check the end of the section
+egrep -q "5.....us : <stack trace>" trace || fail
+
+# Check for 500ms of latency
+egrep -q "latency: 5..... us" trace || fail
+
+reset_tracer
+
+# Simulate irqsoff section for half a second couple of times
+echo irqsoff > current_tracer
+sleep 1
+modprobe $MOD test_mode=irq delay=500000 || fail
+rmmod $MOD || fail
+modprobe $MOD test_mode=irq delay=500000 || fail
+rmmod $MOD || fail
+modprobe $MOD test_mode=irq delay=500000 || fail
+rmmod $MOD || fail
+
+cat trace
+
+# Confirm which tracer
+grep -q "tracer: irqsoff" trace || fail
+
+# Check the end of the section
+egrep -q "5.....us : <stack trace>" trace || fail
+
+# Check for 500ms of latency
+egrep -q "latency: 5..... us" trace || fail
+
+reset_tracer
+exit 0
-- 
2.18.0.203.gfac676dfb9-goog

Re: [PATCH 2/2] kselftests: Add tests for the preemptoff and irqsoff tracers

[Steven Rostedt]

On Tue, 10 Jul 2018 23:35:40 -0700
Joel Fernandes <joel@joelfernandes.org> wrote:

> From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
> 
> Here we add unit tests for the preemptoff and irqsoff tracer by using a
> kernel module introduced previously to trigger long preempt or irq
> disabled sections in the kernel.
> 
> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
> Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> ---
>

I added this to my queue too.

If you are curious to see what's currently in my queue, I just pushed
my queue to my tree:

 git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git

  ftrace/core

Beware, that branch can and will rebase often.

-- Steve