rcu: Don't bother affinitying rcub kthreads away from offline CPUs (5d0b0249) · Commits · 戴 / test

When rcu_boost_kthread_setaffinity() sees that all CPUs for a given rcu_node structure are now offline, it affinities the corresponding RCU-boost ("rcub") kthread away from those CPUs. This is pointless because the kthread cannot run on those offline CPUs in any case. This commit therefore removes this unneeded code. Signed-off-by:

Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcu/tree_plugin.h

+1 −5

Original line number	Diff line number	Diff line
		@@ -1322,12 +1322,8 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
		for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1)
		if ((mask & 0x1) && cpu != outgoingcpu)
		cpumask_set_cpu(cpu, cm);
		if (cpumask_weight(cm) == 0) {
		if (cpumask_weight(cm) == 0)
		cpumask_setall(cm);
		for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++)
		cpumask_clear_cpu(cpu, cm);
		WARN_ON_ONCE(cpumask_weight(cm) == 0);
		}
		set_cpus_allowed_ptr(t, cm);
		free_cpumask_var(cm);
		}

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