Messages in this thread | | | Date | Tue, 17 Feb 2009 13:25:44 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 1/4] generic-smp: remove single ipi fallback for smp_call_function_many() |
| |
On 02/16, Oleg Nesterov wrote: > > > + data->refs = cpumask_weight(&data->cpumask); > > + > > + spin_lock_irqsave(&call_function.lock, flags); > > + call_function.counter++; > > + list_add_tail_rcu(&data->csd.list, &call_function.queue); > > + spin_unlock_irqrestore(&call_function.lock, flags); > > What if the initialization above leaks into the critical section? > > I mean, generic_smp_call_function_interrupt() running on another CPU > can see the result of list_add_tail_rcu() and cpumask_and(data->cpumask) > but not (say) "data->refs = ...".
I was wrong, sorry.
list_add_tail_rcu() implies wmb() and list_for_each_entry_rcu() does smp_read_barrier_depends(), so another CPU must always see the fully initialized entry.
Oleg.
| |