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SubjectRe: Testing tracer wakeup_rt: .. no entries found ..FAILED!
On Tue, Jul 31, 2012 at 08:09:38PM -0400, Steven Rostedt wrote:
> On Tue, 2012-07-31 at 16:57 -0700, Paul E. McKenney wrote:
>
> > > What was the next lines? I bet you it was "PASSED". Which means it did
> > > not fail. This is the second bug you found that has to do with RCU being
> > > called in 'idle'. The one that Paul posted a patch for.
> >
> > Though it needs another patch to actually use it in the right place...
>
> Right. Something like this:

Looks good to me!

Thanx, Paul

> -- Steve
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 5638104..d915638 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -631,7 +631,12 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
>
> memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
> max_data->pid = tsk->pid;
> - max_data->uid = task_uid(tsk);
> + /*
> + * task_uid() calls rcu_read_lock, but this can be called
> + * outside of RCU state monitoring (irq going back to idle).
> + */
> + RCU_NONIDLE(max_data->uid = task_uid(tsk));
> +
> max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
> max_data->policy = tsk->policy;
> max_data->rt_priority = tsk->rt_priority;
>
>



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