2013/2/18 Vincent Guittot <vincent.guit...@linaro.org>: > On 18 February 2013 15:38, Frederic Weisbecker <fweis...@gmail.com> wrote: >> I pasted the original at: http://pastebin.com/DMm5U8J8 > > We can clear the idle flag only in the nohz_kick_needed which will not > be called if the sched_domain is NULL so the sequence will be > > = CPU 0 = = CPU 1= > > detach_and_destroy_domain { > rcu_assign_pointer(cpu1_dom, NULL); > } > > dom = new_domain(...) { > nr_cpus_busy = 0; > set_idle(CPU 1); > } > dom = > rcu_dereference(cpu1_dom) > //dom == NULL, return > > rcu_assign_pointer(cpu1_dom, dom); > > dom = > rcu_dereference(cpu1_dom) > //dom != NULL, > nohz_kick_needed { > > set_idle(CPU 1) > dom > = rcu_dereference(cpu1_dom) > > //dec nr_cpus_busy, > } > > Vincent
Ok but CPU 0 can assign NULL to the domain of cpu1 while CPU 1 is already in the middle of nohz_kick_needed(). _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
