Hello, On Mon, 29 Apr 2013, Paul E. McKenney wrote: > On Tue, Apr 30, 2013 at 12:08:18AM +0300, Julian Anastasov wrote: > > > > Hello, > > > > On Sat, 27 Apr 2013, Paul E. McKenney wrote: > > > > > I would instead suggest something like: > > > > > > #ifndef CONFIG_PREEMPT_RCU > > > > > > But yes, in the CONFIG_PREEMPT_RCU case, the cond_resched() is not > > > needed. > > > > Hm, is this correct? If I follow the ifdefs > > preempt_schedule is called when CONFIG_PREEMPT is > > defined _and_ CONFIG_PREEMPT_RCU is not defined. > > Your example for CONFIG_PREEMPT_RCU is the opposite to this? > > Yep, I really did intend to say "#ifndef CONFIG_PREEMPT_RCU". > > A couple of things to keep in mind: > > 1. Although rcu_read_unlock() does map to preempt_enable() for > CONFIG_TINY_RCU and CONFIG_TREE_RCU, the current Kconfig refuses > to allow either CONFIG_TINY_RCU or CONFIG_TREE_RCU to be selected > if CONFIG_PREEMPT=y. I see, CONFIG_PREEMPT_RCU depends on CONFIG_PREEMPT > 2. In the CONFIG_PREEMPT_RCU case, __rcu_read_unlock() will check > to see if the RCU core needs to be informed, so there is no > need to invoke cond_resched() in that case. OK > 3. If we drop your "|| defined(CONFIG_PREEMPT_RCU)", we get an > almost-synonym for my "#ifndef CONFIG_PREEMPT_RCU". The "almost" > applies to older kernels due to the possibility of having a > CONFIG_TINY_PREEMPT_RCU kernel -- but this possibility is going > away soon. > > Make sense? Yes, thanks for the explanation! Simon, so lets do it as suggested by Eric and Paul: rcu_read_unlock(); #ifndef CONFIG_PREEMPT_RCU cond_resched(); #endif rcu_read_lock(); Regards -- Julian Anastasov <ja@xxxxxx> -- 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
