diff options
| -rw-r--r-- | kernel/rcu/tree_stall.h | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 8bde1b53b0c9..65302518e006 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -723,6 +723,10 @@ static void check_cpu_stall(struct rcu_data *rdp) * count this as an RCU priority boosting failure. A return of true says * RCU priority boosting is to blame, and false says otherwise. If false * is returned, the first of the CPUs to blame is stored through cpup. + * If there was no CPU blocking the current grace period, but also nothing + * in need of being boosted, *cpup is set to -1. This can happen in case + * of vCPU preemption while the last CPU is reporting its quiscent state, + * for example. * * If cpup is NULL, then a lockless quick check is carried out, suitable * for high-rate usage. On the other hand, if cpup is non-NULL, each @@ -730,18 +734,25 @@ static void check_cpu_stall(struct rcu_data *rdp) */ bool rcu_check_boost_fail(unsigned long gp_state, int *cpup) { + bool atb = false; int cpu; unsigned long flags; struct rcu_node *rnp; rcu_for_each_leaf_node(rnp) { if (!cpup) { - if (READ_ONCE(rnp->qsmask)) + if (READ_ONCE(rnp->qsmask)) { return false; - else + } else { + if (READ_ONCE(rnp->gp_tasks)) + atb = true; continue; + } } + *cpup = -1; raw_spin_lock_irqsave_rcu_node(rnp, flags); + if (rnp->gp_tasks) + atb = true; if (!rnp->qsmask) { // No CPUs without quiescent states for this rnp. raw_spin_unlock_irqrestore_rcu_node(rnp, flags); @@ -758,7 +769,7 @@ bool rcu_check_boost_fail(unsigned long gp_state, int *cpup) raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } // Can't blame CPUs, so must blame RCU priority boosting. - return true; + return atb; } EXPORT_SYMBOL_GPL(rcu_check_boost_fail); |