On Wed, Jul 11, 2018 at 09:19:44AM -0400, Steven Rostedt wrote: > > > protection to prevent something like the following case: a spin_lock is > > > taken. Then lockdep_acquired is called. That does a raw_local_irq_save > > > and then sets lockdep_recursion, and then calls __lockdep_acquired. In > > > this function, a call to get_lock_stats happens which calls > > > preempt_disable, which calls trace IRQS off somewhere which enters my > > > tracepoint code and sets the tracing_irq_cpu flag to prevent recursion. > > > This flag is then never cleared causing lockdep paths to never be > > > entered and thus causing splats and other bad things. > > > > Would it not be much easier to avoid that entirely, afaict all > > get/put_lock_stats() callers already have IRQs disabled, so that > > (traced) preempt fiddling is entirely superfluous. > > Agreed. Looks like a good clean up. So actually with or without the clean up, I don't see any issues with dropping lockdep_recursing in my tests at the moment. I'm not sure something else changed between then and now causing the issue to go away. I can include Peter's clean up in my series though if he's Ok with it since you guys agree its a good clean up anyway. Would you prefer I did that, and then also dropped the lockdep_recursing checks? Or should I keep the lockdep_recursing() checks just to be safe? Do you see cases where you want irqsoff tracing while lockdep_recursing() is true? thanks, - Joel -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
