tracing: Robustify wait loop

tracing: Robustify wait loop

The pending nested sleep debugging triggered on the potential stale
TASK_INTERRUPTIBLE in this code.

While there, fix the loop such that we won't revert to a while(1)
yield() 'spin' loop if we ever get a spurious wakeup.

And fix the actual issue by properly terminating the 'wait' loop by
setting TASK_RUNNING.

Link: http://lkml.kernel.org/p/[email protected]
Reported-by: Fengguang Wu <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>