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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>
This commit is contained in:
Steven Rostedt 2014-10-08 13:52:16 -04:00
parent fe0e01c77d
commit addff1feb0
1 changed files with 30 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
kernel/trace/trace_selftest.c
View File

@ -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);