Messages in this thread |  | | | Date | Sat, 6 Nov 2010 15:42:19 -0400 | | From | Mathieu Desnoyers <> | | Subject | Re: [PATCH] a local-timer-free version of RCU |
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* Mathieu Desnoyers (mathieu.desnoyers@efficios.com) wrote: > > > +/** > > > + * rcu_read_unlock - marks the end of an RCU read-side critical section. > > > + * Check if a RCU batch was started while we were in the critical > > > + * section. If so, call rcu_quiescent() join the rendezvous. > > > + * > > > + * See rcu_read_lock() for more information. > > > + */ > > > +void __rcu_read_unlock(void) > > > +{ > > > + struct rcu_data *r; > > > + int cpu, flags; > > > + > > Another memory barrier would be needed here to ensure that the memory accesses > performed within the C.S. are not reordered wrt nest_count decrement.
Nevermind. xchg() acts as a memory barrier, and nest_count is only ever touched by the local CPU. No memory barrier needed here.
Thanks,
Mathieu
> > > > + cpu = smp_processor_id(); > > > + r = &per_cpu(rcu_data, cpu); > > > + if (--r->nest_count == 0) { > > > + flags = xchg(&r->flags, 0); > > > + if (flags & DO_RCU_COMPLETION) > > > + rcu_quiescent(cpu); > > > + } > > > +} > > > +EXPORT_SYMBOL(__rcu_read_unlock); > > Thanks, > > Mathieu > > -- > Mathieu Desnoyers > Operating System Efficiency R&D Consultant > EfficiOS Inc. > http://www.efficios.com
-- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com
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