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>

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 7f3244c0df014a7673831159ae1dbc25ceff55c8..b1b4851113212046a2f49c943d026b6cd50be887 100644 (file)
--- 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;
 }