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tracing: Clean up scheduling in trace_wakeup_test_thread()
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> Acked-by: Peter Zijlstra <peterz@infreadead.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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@ -1025,6 +1025,12 @@ trace_selftest_startup_nop(struct tracer *trace, struct trace_array *tr)
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#endif
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#ifdef CONFIG_SCHED_TRACER
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struct wakeup_test_data {
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struct completion is_ready;
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int go;
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};
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static int trace_wakeup_test_thread(void *data)
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{
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/* Make this a -deadline thread */
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@ -1034,51 +1040,56 @@ static int trace_wakeup_test_thread(void *data)
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.sched_deadline = 10000000ULL,
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.sched_period = 10000000ULL
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};
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struct completion *x = data;
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struct wakeup_test_data *x = data;
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sched_setattr(current, &attr);
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/* Make it know we have a new prio */
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complete(x);
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complete(&x->is_ready);
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/* now go to sleep and let the test wake us up */
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set_current_state(TASK_INTERRUPTIBLE);
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schedule();
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while (!x->go) {
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schedule();
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set_current_state(TASK_INTERRUPTIBLE);
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}
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complete(x);
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complete(&x->is_ready);
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set_current_state(TASK_INTERRUPTIBLE);
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/* we are awake, now wait to disappear */
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while (!kthread_should_stop()) {
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/*
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* This will likely be the system top priority
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* task, do short sleeps to let others run.
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*/
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msleep(100);
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schedule();
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set_current_state(TASK_INTERRUPTIBLE);
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}
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__set_current_state(TASK_RUNNING);
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return 0;
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}
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int
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trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
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{
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unsigned long save_max = tr->max_latency;
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struct task_struct *p;
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struct completion is_ready;
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struct wakeup_test_data data;
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unsigned long count;
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int ret;
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init_completion(&is_ready);
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memset(&data, 0, sizeof(data));
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init_completion(&data.is_ready);
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/* create a -deadline thread */
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p = kthread_run(trace_wakeup_test_thread, &is_ready, "ftrace-test");
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p = kthread_run(trace_wakeup_test_thread, &data, "ftrace-test");
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if (IS_ERR(p)) {
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printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
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return -1;
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}
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/* make sure the thread is running at -deadline policy */
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wait_for_completion(&is_ready);
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wait_for_completion(&data.is_ready);
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/* start the tracing */
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ret = tracer_init(trace, tr);
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@ -1099,18 +1110,20 @@ trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
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msleep(100);
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}
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init_completion(&is_ready);
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init_completion(&data.is_ready);
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data.go = 1;
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/* memory barrier is in the wake_up_process() */
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wake_up_process(p);
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/* Wait for the task to wake up */
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wait_for_completion(&is_ready);
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wait_for_completion(&data.is_ready);
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/* stop the tracing. */
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tracing_stop();
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/* check both trace buffers */
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ret = trace_test_buffer(&tr->trace_buffer, NULL);
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printk("ret = %d\n", ret);
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if (!ret)
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ret = trace_test_buffer(&tr->max_buffer, &count);
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