On Wed, May 29, 2019 at 09:42:13AM -0400, Steven Rostedt wrote: > > And the preempt_irqoff tracer had better also consume the IRQ events, > > and if it does that it can DTRT without extra bits on, even with that > > race. > > > > Consider: > > > > preempt_disable() > > preempt_count += 1; > > <IRQ> > > trace_irq_enter(); > > > > trace_irq_exit(); > > </IRQ> > > trace_preempt_disable(); > > > > /* does stuff */ > > > > preempt_enable() > > preempt_count -= 1; > > trace_preempt_enable(); > > > > You're saying preempt_irqoff() fails to connect the two because of the > > hole between trace_irq_exit() and trace_preempt_disable() ? > > > > But trace_irq_exit() can see the raised preempt_count and set state > > for trace_preempt_disable() to connect. > > That's basically what I was suggesting as the solution to this ;-)
You were wanting changes to preempt_disable() and task_struct, neither of which is required. The above only needs some per-cpu storage in the tracer implementation.
