diff options
Diffstat (limited to 'kernel/rcu/tree_stall.h')
| -rw-r--r-- | kernel/rcu/tree_stall.h | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 59b95cc5cbdf..af92d9fee0d4 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -717,6 +717,42 @@ static void check_cpu_stall(struct rcu_data *rdp) /* + * Check to see if a failure to end RCU priority inversion was due to + * a CPU not passing through a quiescent state. When this happens, there + * is nothing that RCU priority boosting can do to help, so we shouldn't + * 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. + */ +bool rcu_check_boost_fail(unsigned long gp_state, int *cpup) +{ + int cpu; + unsigned long flags; + struct rcu_node *rnp; + + rcu_for_each_leaf_node(rnp) { + raw_spin_lock_irqsave_rcu_node(rnp, flags); + if (!rnp->qsmask) { + // No CPUs without quiescent states for this rnp. + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + continue; + } + // Find the first holdout CPU. + for_each_leaf_node_possible_cpu(rnp, cpu) { + if (rnp->qsmask & (1UL << (cpu - rnp->grplo))) { + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + *cpup = cpu; + return false; + } + } + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + } + // Can't blame CPUs, so must blame RCU priority boosting. + return true; +} +EXPORT_SYMBOL_GPL(rcu_check_boost_fail); + +/* * Show the state of the grace-period kthreads. */ void show_rcu_gp_kthreads(void) |