Messages in this thread | | | Date | Fri, 29 Aug 2008 23:23:30 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH] Remove stop_machine during module load |
| |
Hi Paul,
Thanks for the excellent review.
On Fri, Aug 29, 2008 at 01:44:57PM -0700, Paul E. McKenney wrote: > > OK, what about the read side? Not so good for __unlink_module() to yank
That's independent from my patch isn't it? I don't think I'm changing anything here. All of the issues you're pointing out are already in the code (except for the missing read_barrier_depends() perhaps)
I think the lockless users like oops or sysrq-t typically have preemption disabled, so they should be ok regarding that.
> the module out from under a reader. Therefore, all readers must either > disable interrupts to block stop_machine() or must hold some sort of > mutex that prevents modules from being unloaded. > > First, where the heck -is- the read side... > > o each_symbol() needs its list_for_each_entry() to become > list_for_each_entry_rcu() and needs local_irq_disable()
Ah that's needed for the Alpha barrier depends semantics, right?
> Yet another approach would be to use call_rcu() to defer the > various kfree() &c calls later in free_module.
I think that would be a the better approach.
-Andi
| |