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-rw-r--r--kernel/rcu/tree_plugin.h90
1 files changed, 79 insertions, 11 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 410c744..31c7afb 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2479,6 +2479,7 @@ void __init rcu_init_nohz(void)
rdp->nxttail[RCU_NEXT_TAIL] != NULL);
init_nocb_callback_list(rdp);
}
+ rcu_organize_nocb_kthreads(rsp);
}
}
@@ -2490,15 +2491,85 @@ static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
rdp->nocb_follower_tail = &rdp->nocb_follower_head;
}
+/*
+ * If the specified CPU is a no-CBs CPU that does not already have its
+ * rcuo kthread for the specified RCU flavor, spawn it. If the CPUs are
+ * brought online out of order, this can require re-organizing the
+ * leader-follower relationships.
+ */
+static void rcu_spawn_one_nocb_kthread(struct rcu_state *rsp, int cpu)
+{
+ struct rcu_data *rdp;
+ struct rcu_data *rdp_last;
+ struct rcu_data *rdp_old_leader;
+ struct rcu_data *rdp_spawn = per_cpu_ptr(rsp->rda, cpu);
+ struct task_struct *t;
+
+ /*
+ * If this isn't a no-CBs CPU or if it already has an rcuo kthread,
+ * then nothing to do.
+ */
+ if (!rcu_is_nocb_cpu(cpu) || rdp_spawn->nocb_kthread)
+ return;
+
+ /* If we didn't spawn the leader first, reorganize! */
+ rdp_old_leader = rdp_spawn->nocb_leader;
+ if (rdp_old_leader != rdp_spawn && !rdp_old_leader->nocb_kthread) {
+ rdp_last = NULL;
+ rdp = rdp_old_leader;
+ do {
+ 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;
+ } while (rdp);
+ rdp_spawn->nocb_next_follower = rdp_old_leader;
+ }
+
+ /* Spawn the kthread for this CPU and RCU flavor. */
+ t = kthread_run(rcu_nocb_kthread, rdp_spawn,
+ "rcuo%c/%d", rsp->abbr, cpu);
+ BUG_ON(IS_ERR(t));
+ ACCESS_ONCE(rdp_spawn->nocb_kthread) = t;
+}
+
+/*
+ * If the specified CPU is a no-CBs CPU that does not already have its
+ * rcuo kthreads, spawn them.
+ */
+static void rcu_spawn_all_nocb_kthreads(int cpu)
+{
+ struct rcu_state *rsp;
+
+ if (rcu_scheduler_fully_active)
+ for_each_rcu_flavor(rsp)
+ rcu_spawn_one_nocb_kthread(rsp, cpu);
+}
+
+/*
+ * Once the scheduler is running, spawn rcuo kthreads for all online
+ * no-CBs CPUs. This assumes that the early_initcall()s happen before
+ * non-boot CPUs come online -- if this changes, we will need to add
+ * some mutual exclusion.
+ */
+static void __init rcu_spawn_nocb_kthreads(void)
+{
+ int cpu;
+
+ for_each_online_cpu(cpu)
+ rcu_spawn_all_nocb_kthreads(cpu);
+}
+
/* How many follower CPU IDs per leader? Default of -1 for sqrt(nr_cpu_ids). */
static int rcu_nocb_leader_stride = -1;
module_param(rcu_nocb_leader_stride, int, 0444);
/*
- * Create a kthread for each RCU flavor for each no-CBs CPU.
- * Also initialize leader-follower relationships.
+ * Initialize leader-follower relationships for all no-CBs CPU.
*/
-static void __init rcu_spawn_nocb_kthreads(struct rcu_state *rsp)
+static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp)
{
int cpu;
int ls = rcu_nocb_leader_stride;
@@ -2506,7 +2577,6 @@ static void __init rcu_spawn_nocb_kthreads(struct rcu_state *rsp)
struct rcu_data *rdp;
struct rcu_data *rdp_leader = NULL; /* Suppress misguided gcc warn. */
struct rcu_data *rdp_prev = NULL;
- struct task_struct *t;
if (rcu_nocb_mask == NULL)
return;
@@ -2532,12 +2602,6 @@ static void __init rcu_spawn_nocb_kthreads(struct rcu_state *rsp)
rdp_prev->nocb_next_follower = rdp;
}
rdp_prev = rdp;
-
- /* Spawn the kthread for this CPU. */
- t = kthread_run(rcu_nocb_kthread, rdp,
- "rcuo%c/%d", rsp->abbr, cpu);
- BUG_ON(IS_ERR(t));
- ACCESS_ONCE(rdp->nocb_kthread) = t;
}
}
@@ -2591,7 +2655,11 @@ static void do_nocb_deferred_wakeup(struct rcu_data *rdp)
{
}
-static void __init rcu_spawn_nocb_kthreads(struct rcu_state *rsp)
+static void rcu_spawn_all_nocb_kthreads(int cpu)
+{
+}
+
+static void __init rcu_spawn_nocb_kthreads(void)
{
}
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