rcu: Correctly handle sparse possible cpus

[cascardo/linux.git] / kernel / rcu / tree.h

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index e3959f5..f714f87 100644 (file)
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -253,6 +253,13 @@ struct rcu_node {
        wait_queue_head_t exp_wq[4];
 } ____cacheline_internodealigned_in_smp;
 
+/*
+ * Bitmasks in an rcu_node cover the interval [grplo, grphi] of CPU IDs, and
+ * are indexed relative to this interval rather than the global CPU ID space.
+ * This generates the bit for a CPU in node-local masks.
+ */
+#define leaf_node_cpu_bit(rnp, cpu) (1UL << ((cpu) - (rnp)->grplo))
+
 /*
  * Do a full breadth-first scan of the rcu_node structures for the
  * specified rcu_state structure.
@@ -280,6 +287,14 @@ struct rcu_node {
        for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
             (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
 
+/*
+ * Iterate over all possible CPUs in a leaf RCU node.
+ */
+#define for_each_leaf_node_possible_cpu(rnp, cpu) \
+       for ((cpu) = cpumask_next(rnp->grplo - 1, cpu_possible_mask); \
+            cpu <= rnp->grphi; \
+            cpu = cpumask_next((cpu), cpu_possible_mask))
+
 /*
  * Union to allow "aggregate OR" operation on the need for a quiescent
  * state by the normal and expedited grace periods.