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authorPaul E. McKenney <>2015-09-29 09:45:00 -0700
committerPaul E. McKenney <>2015-12-04 12:26:50 -0800
commit1de6e56ddc043437d335ee0455a1b34b73510c91 (patch)
parent06f60de19d3141f07d954c9275fe7ccca8e96b42 (diff)
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 <>
1 files changed, 2 insertions, 0 deletions
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. */