Commit-ID: bbe5d7a93a39104be146f71b9b99af8fb65a6a2d
Gitweb: http://git.kernel.org/tip/bbe5d7a93a39104be146f71b9b99af8fb65a6a2d
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Fri, 24 Oct 2014 11:11:08 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Wed, 29 Oct 2014 10:20:08 -0700
rcu: Fix for rcuo online-time-creation reorganization bug
Commit 35ce7f29a44a (rcu: Create rcuo kthreads only for onlined CPUs)
contains checks for the case where CPUs are brought online out of
order, re-wiring the rcuo leader-follower relationships as needed.
Unfortunately, this rewiring was broken. This apparently went undetected
due to the tendency of systems to bring CPUs online in order. This commit
nevertheless fixes the rewiring.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree_plugin.h | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 6d07fb4..5053dae 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2586,9 +2586,13 @@ static void rcu_spawn_one_nocb_kthread(struct rcu_state *rsp, int cpu)
rdp->nocb_leader = rdp_spawn;
if (rdp_last && rdp != rdp_spawn)
rdp_last->nocb_next_follower = rdp;
- rdp_last = rdp;
- rdp = rdp->nocb_next_follower;
- rdp_last->nocb_next_follower = NULL;
+ if (rdp == rdp_spawn) {
+ rdp = rdp->nocb_next_follower;
+ } else {
+ rdp_last = rdp;
+ rdp = rdp->nocb_next_follower;
+ rdp_last->nocb_next_follower = NULL;
+ }
} while (rdp);
rdp_spawn->nocb_next_follower = rdp_old_leader;
}
--
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