On Mon, Oct 29, 2018 at 11:07:06AM -0700, Douglas Anderson wrote: > In kgdb_roundup_cpus() we've got code that looks like: > local_irq_enable(); > smp_call_function(kgdb_call_nmi_hook, NULL, 0); > local_irq_disable(); > Let's add kgdb to the list of reasons not to warn in > smp_call_function_many(). That will allow us (in a future patch) to > stop calling local_irq_enable() which will get rid of the original > splat. > > NOTE: with this change comes the obvious question: will we start > deadlocking more often now when we drop into the debugger. I can't > say that for sure one way or the other, but the fact that we do the > same logic for "oops_in_progress" makes me feel like it shouldn't > happen too often. Also note that the old logic of turning on > interrupts temporarily wasn't exactly safe since (I presume) that > could have violated spin_lock_irqsave() semantics and ended up with a > deadlock of its own. How is any of that not utterly and terminally broken? > @@ -413,7 +414,8 @@ void smp_call_function_many(const struct cpumask *mask, > * can't happen. > */ > WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() > - && !oops_in_progress && !early_boot_irqs_disabled); > + && !oops_in_progress && !early_boot_irqs_disabled > + && !in_dbg_master()); > > /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ > cpu = cpumask_first_and(mask, cpu_online_mask); Not a fan of this. There is a distinct difference between oops_in_progress and dropping into kgdb in that you don't ever expect to return/survive oopses, whereas we do expect to survive kgdb. Also, how does kgdb work at all without actual NMIs ? So no, NAK on this.
