From 5d8a752e31aaa4c9703f201956a40b45ed791217 Mon Sep 17 00:00:00 2001 From: Zhouyi Zhou Date: Wed, 20 Mar 2019 03:33:00 +0000 Subject: [PATCH] rcu: Fix force_qs_rnp() header comment Previously, threads blocked on offlining CPUS were migrated to the root rcu_node structure, thus requiring RCU priority boosting on this structure. However, since commit d19fb8d1f3f6 ("rcu: Don't migrate blocked tasks even if all corresponding CPUs offline"), RCU does not migrate blocked tasks. Consequently, RCU no longer does RCU priority boosting on the root rcu_node structure as of commit 1be0085b515e ("rcu: Don't initiate RCU priority boosting on root rcu_node"). This commit therefore brings comments for the force_qs_rnp() function's header comment in line with this new no-root-boosting reality. Signed-off-by: Zhouyi Zhou [ paulmck: Also remove obsolete comment on suppressing new grace periods. ] Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index e117732bcd5d..abc8512ceb5f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2548,11 +2548,11 @@ void rcu_sched_clock_irq(int user) } /* - * Scan the leaf rcu_node structures, processing dyntick state for any that - * have not yet encountered a quiescent state, using the function specified. - * Also initiate boosting for any threads blocked on the root rcu_node. - * - * The caller must have suppressed start of new grace periods. + * Scan the leaf rcu_node structures. For each structure on which all + * CPUs have reported a quiescent state and on which there are tasks + * blocking the current grace period, initiate RCU priority boosting. + * Otherwise, invoke the specified function to check dyntick state for + * each CPU that has not yet reported a quiescent state. */ static void force_qs_rnp(int (*f)(struct rcu_data *rdp)) {