On Thu, Apr 23, 2009 at 02:11:58PM +0800, Lai Jiangshan wrote: > Paul E. McKenney wrote: [ . . . ] > Hi, Paul > > I just typed codes in email, very like these two pathes: > > [PATCH 1/2] sched: Introduce APIs for waiting multi events > http://lkml.org/lkml/2009/4/14/733 > > [PATCH 2/2] rcupdate: use struct ref_completion > http://lkml.org/lkml/2009/4/14/734 > > Lai. > -------------- Interesting approach! This would get a second use for your multi-events waiting code above. ;-) Looks like the idea is to have the task doing the synchronize_rcu_bh_expedited() hold a reference across the process, and have each rcu_bh_fast_qs() also acquire a reference, which would be released in the softirq handler synchronize_rcu_bh_expedited_help(). One question -- does this approach correctly handle all the CPU hotplug scenarios? (I think that it might, but am not completely certain.) Thanx, Paul > #ifndef CONFIG_SMP > > static void __init synchronize_rcu_expedited_init(void) > { > } > > void synchronize_rcu_bh_expedited(void) > { > cond_resched(); > } > > #else /* #ifndef CONFIG_SMP */ > > static DEFINE_MUTEX(synchronize_rcu_bh_mutex); > static DEFINE_PER_CPU(int, call_only_once); /* is it need ? */ > static struct ref_completion rcu_bh_expedited_completion > > static void synchronize_rcu_bh_expedited_help(struct softirq_action *unused) > { > if (__get_cpu_var(call_only_once)) { > smp_mb(); > ref_completion_put(&rcu_bh_expedited_completion); > __get_cpu_var(call_only_once) = 0; > } > } > > static void rcu_bh_fast_qs(void *unused) > { > __get_cpu_var(call_only_once) = 1; > ref_completion_get(&rcu_bh_expedited_completion); > raise_softirq(RCU_EXPEDITED_SOFTIRQ); > } > > static void __init synchronize_rcu_expedited_init(void) > { > open_softirq(RCU_EXPEDITED_SOFTIRQ, synchronize_rcu_bh_expedited_help); > } > > void synchronize_rcu_bh_expedited(void) > { > mutex_lock(&synchronize_rcu_bh_mutex); > > ref_completion_get_init(&rcu_bh_expedited_completion); > > smp_call_function(rcu_bh_fast_qs, NULL, 1); > > ref_completion_put_init(&rcu_bh_expedited_completion); > ref_completion_wait(&rcu_bh_expedited_completion); > > mutex_unlock(&synchronize_rcu_bh_mutex); > } > > #endif /* #else #ifndef CONFIG_SMP */ > -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
