Messages in this thread | | | Date | Mon, 14 Mar 2011 18:09:28 -0400 | From | Joe Korty <> | Subject | Re: [PATCH 8/9] jrcu: fix broken rcu_barrier |
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On Mon, Mar 14, 2011 at 04:47:18AM -0400, Paul E. McKenney wrote: > On Sun, Mar 13, 2011 at 11:50:44PM -0400, Joe Korty wrote: > > +void rcu_barrier(void) > > +{ > > + synchronize_sched(); > > + synchronize_sched(); > > +} > > This is still broken. You need to wait until all pre-existing RCU > callbacks on all CPUs have been invoked. Although this does guarantee > that all callbacks on the current CPU have been invoked, if one of the > other CPUs is busy, it might not yet have processed the callbacks from > earlier grace periods. The usual way to take care of this is to post > a callback on each CPU, then wait for them all to be invoked.
Hi Paul, JRCU (eventually) chains together all callbacks from all cpus into a single queue and then it expires that single queue. So the double synchronize_sched() should work as a rcu_barrier implementation.
Thanks, Joe
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