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rcu: Refine diagnostics for lacking kthread for no-CBs callbacks

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Some diagnostics under CONFIG_PROVE_RCU in rcu_nocb_cpu_needs_barrier()
assume that there can be no early-boot callbacks.  This commit therefore
qualifies the diagnostic with rcu_scheduler_fully_active to permit
early boot callbacks to avoid this splat.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2015-01-19 21:43:40 -08:00
parent 143da9c2fc
commit 59f792d1ef
1 changed files with 2 additions and 1 deletions
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3
kernel/rcu/tree_plugin.h
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@ -1945,7 +1945,8 @@ static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu)
rhp = ACCESS_ONCE(rdp->nocb_follower_head);
/* Having no rcuo kthread but CBs after scheduler starts is bad! */
if (!ACCESS_ONCE(rdp->nocb_kthread) && rhp) {
if (!ACCESS_ONCE(rdp->nocb_kthread) && rhp &&
rcu_scheduler_fully_active) {
/* RCU callback enqueued before CPU first came online??? */
pr_err("RCU: Never-onlined no-CBs CPU %d has CB %p\n",
cpu, rhp->func);