rcu: Properly initialize ->boost_tasks on CPU offline

When rcu_preempt_offline_tasks() clears tasks from a leaf rcu_node
structure, it does not NULL out the structure's ->boost_tasks field.
This commit therefore fixes this issue.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 7f3244c0df01..b1b485111321 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -584,8 +584,11 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
                 raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
         }
 
+        rnp->gp_tasks = NULL;
+        rnp->exp_tasks = NULL;
 #ifdef CONFIG_RCU_BOOST
-        /* In case root is being boosted and leaf is not. */
+        rnp->boost_tasks = NULL;
+        /* In case root is being boosted and leaf was not. */
         raw_spin_lock(&rnp_root->lock); /* irqs already disabled */
         if (rnp_root->boost_tasks != NULL &&
             rnp_root->boost_tasks != rnp_root->gp_tasks)
@@ -593,8 +596,6 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
         raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
 #endif /* #ifdef CONFIG_RCU_BOOST */
 
-        rnp->gp_tasks = NULL;
-        rnp->exp_tasks = NULL;
         return retval;
 }