From 1de6e56ddc043437d335ee0455a1b34b73510c91 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 29 Sep 2015 09:45:00 -0700 Subject: [PATCH] rcu: Clarify role of ->expmaskinitnext Analogy with the ->qsmaskinitnext field might lead one to believe that ->expmaskinitnext tracks online CPUs. This belief is incorrect: Any CPU that has ever been online will have its bit set in the ->expmaskinitnext field. This commit therefore adds a comment to make this clear, at least to people who read comments. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index f32bebb6bc90..8151971a8978 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -178,6 +178,8 @@ struct rcu_node { /* beginning of each expedited GP. */ unsigned long expmaskinitnext; /* Online CPUs for next expedited GP. */ + /* Any CPU that has ever been online will */ + /* have its bit set. */ unsigned long grpmask; /* Mask to apply to parent qsmask. */ /* Only one bit will be set in this mask. */ int grplo; /* lowest-numbered CPU or group here. */ -- 2.20.1