lkml.org 
[lkml]   [2014]   [Oct]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[for-next][PATCH 2/2] tracing: Clean up scheduling in trace_wakeup_test_thread()
From: Steven Rostedt <rostedt@goodmis.org>

Peter's new debugging tool triggers when tasks exit with !TASK_RUNNING.
The code in trace_wakeup_test_thread() also has a single schedule() call
that should be encompassed by a loop.

This cleans up the code a little to make it a bit more robust and
also makes the return exit properly with TASK_RUNNING.

Link: http://lkml.kernel.org/p/20141008135216.76142204@gandalf.local.home

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_selftest.c | 47 +++++++++++++++++++++++++++----------------
1 file changed, 30 insertions(+), 17 deletions(-)

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 5ef60499dc8e..593f52b73551 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -1025,6 +1025,12 @@ trace_selftest_startup_nop(struct tracer *trace, struct trace_array *tr)
#endif

#ifdef CONFIG_SCHED_TRACER
+
+struct wakeup_test_data {
+ struct completion is_ready;
+ int go;
+};
+
static int trace_wakeup_test_thread(void *data)
{
/* Make this a -deadline thread */
@@ -1034,51 +1040,56 @@ static int trace_wakeup_test_thread(void *data)
.sched_deadline = 10000000ULL,
.sched_period = 10000000ULL
};
- struct completion *x = data;
+ struct wakeup_test_data *x = data;

sched_setattr(current, &attr);

/* Make it know we have a new prio */
- complete(x);
+ complete(&x->is_ready);

/* now go to sleep and let the test wake us up */
set_current_state(TASK_INTERRUPTIBLE);
- schedule();
+ while (!x->go) {
+ schedule();
+ set_current_state(TASK_INTERRUPTIBLE);
+ }

- complete(x);
+ complete(&x->is_ready);
+
+ set_current_state(TASK_INTERRUPTIBLE);

/* we are awake, now wait to disappear */
while (!kthread_should_stop()) {
- /*
- * This will likely be the system top priority
- * task, do short sleeps to let others run.
- */
- msleep(100);
+ schedule();
+ set_current_state(TASK_INTERRUPTIBLE);
}

+ __set_current_state(TASK_RUNNING);
+
return 0;
}
-
int
trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
{
unsigned long save_max = tr->max_latency;
struct task_struct *p;
- struct completion is_ready;
+ struct wakeup_test_data data;
unsigned long count;
int ret;

- init_completion(&is_ready);
+ memset(&data, 0, sizeof(data));
+
+ init_completion(&data.is_ready);

/* create a -deadline thread */
- p = kthread_run(trace_wakeup_test_thread, &is_ready, "ftrace-test");
+ p = kthread_run(trace_wakeup_test_thread, &data, "ftrace-test");
if (IS_ERR(p)) {
printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
return -1;
}

/* make sure the thread is running at -deadline policy */
- wait_for_completion(&is_ready);
+ wait_for_completion(&data.is_ready);

/* start the tracing */
ret = tracer_init(trace, tr);
@@ -1099,18 +1110,20 @@ trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
msleep(100);
}

- init_completion(&is_ready);
+ init_completion(&data.is_ready);
+
+ data.go = 1;
+ /* memory barrier is in the wake_up_process() */

wake_up_process(p);

/* Wait for the task to wake up */
- wait_for_completion(&is_ready);
+ wait_for_completion(&data.is_ready);

/* stop the tracing. */
tracing_stop();
/* check both trace buffers */
ret = trace_test_buffer(&tr->trace_buffer, NULL);
- printk("ret = %d\n", ret);
if (!ret)
ret = trace_test_buffer(&tr->max_buffer, &count);

--
2.0.1



\
 
 \ /
  Last update: 2014-10-09 03:42    [W:0.060 / U:0.224 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site