rcu: Check for have_rcu_nocb_mask instead of rcu_nocb_mask

If we configure a kernel with CONFIG_NOCB_CPU=y, CONFIG_RCU_NOCB_CPU_NONE=y and
CONFIG_CPUMASK_OFFSTACK=n and do not pass in a rcu_nocb= boot parameter, the
cpumask rcu_nocb_mask can be garbage instead of NULL.

Hence this commit replaces checks for rcu_nocb_mask == NULL with a check for
have_rcu_nocb_mask.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 31c7afb611fdb8ca179b3cad165e864f75486653..39e68bcf6d83a3e91873039dfe321f103ad94f60 100644 (file)
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2578,7 +2578,7 @@ static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp)
        struct rcu_data *rdp_leader = NULL;  /* Suppress misguided gcc warn. */
        struct rcu_data *rdp_prev = NULL;
 
-       if (rcu_nocb_mask == NULL)
+       if (!have_rcu_nocb_mask)
                return;
        if (ls == -1) {
                ls = int_sqrt(nr_cpu_ids);
@@ -2608,9 +2608,9 @@ static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp)
 /* Prevent __call_rcu() from enqueuing callbacks on no-CBs CPUs */
 static bool init_nocb_callback_list(struct rcu_data *rdp)
 {
-       if (rcu_nocb_mask == NULL ||
-           !cpumask_test_cpu(rdp->cpu, rcu_nocb_mask))
+       if (!rcu_is_nocb_cpu(rdp->cpu))
                return false;
+
        rdp->nxttail[RCU_NEXT_TAIL] = NULL;
        return true;
 }