If we return -1 in the ops->stack for the stacktrace saving, we end up
breaking out of the loop if the stack we are tracing is in the exception
stack. This causes traces like:
<idle>-0 [002] 34263.745825: raise_softirq_irqoff <-__blk_complete_request
<idle>-0 [002] 34263.745826:
<= 0
<= 0
<= 0
<= 0
<= 0
<= 0
<= 0
By returning "0" instead, the irq stack is saved as well, and we see:
<idle>-0 [003] 883.280992: raise_softirq_irqoff <-__hrtimer_star
t_range_ns
<idle>-0 [003] 883.280992:
<= hrtimer_start_range_ns
<= tick_nohz_restart_sched_tick
<= cpu_idle
<= start_secondary
<=
<= 0
<= 0
[ Impact: record stacks from interrupts ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
29a679754b