rcu: Add nocb_cb_kthread check to rcu_is_callbacks_kthread()

Callbacks are invoked in RCU kthreads when calbacks are offloaded
(rcu_nocbs boot parameter) or when RCU's softirq handler has been
offloaded to rcuc kthreads (use_softirq==0).  The current code allows
for the rcu_nocbs case but not the use_softirq case.  This commit adds
support for the use_softirq case.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c25ba44..7445567 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2530,7 +2530,7 @@ static void rcu_do_batch(struct rcu_data *rdp)
                trace_rcu_batch_end(rcu_state.name, 0,
                                    !rcu_segcblist_empty(&rdp->cblist),
                                    need_resched(), is_idle_task(current),
-                                   rcu_is_callbacks_kthread());
+                                   rcu_is_callbacks_kthread(rdp));
                return;
        }
 
@@ -2608,7 +2608,7 @@ static void rcu_do_batch(struct rcu_data *rdp)
        rcu_nocb_lock_irqsave(rdp, flags);
        rdp->n_cbs_invoked += count;
        trace_rcu_batch_end(rcu_state.name, count, !!rcl.head, need_resched(),
-                           is_idle_task(current), rcu_is_callbacks_kthread());
+                           is_idle_task(current), rcu_is_callbacks_kthread(rdp));
 
        /* Update counts and requeue any remaining callbacks. */
        rcu_segcblist_insert_done_cbs(&rdp->cblist, &rcl);

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 4f8532c..649ad4f 100644 (file)
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -426,7 +426,7 @@ static void rcu_flavor_sched_clock_irq(int user);
 static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck);
 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
-static bool rcu_is_callbacks_kthread(void);
+static bool rcu_is_callbacks_kthread(struct rcu_data *rdp);
 static void rcu_cpu_kthread_setup(unsigned int cpu);
 static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp);
 static bool rcu_preempt_has_tasks(struct rcu_node *rnp);

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index c8ba0fe..0483e13 100644 (file)
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1012,6 +1012,25 @@ static void rcu_cpu_kthread_setup(unsigned int cpu)
        WRITE_ONCE(rdp->rcuc_activity, jiffies);
 }
 
+static bool rcu_is_callbacks_nocb_kthread(struct rcu_data *rdp)
+{
+#ifdef CONFIG_RCU_NOCB_CPU
+       return rdp->nocb_cb_kthread == current;
+#else
+       return false;
+#endif
+}
+
+/*
+ * Is the current CPU running the RCU-callbacks kthread?
+ * Caller must have preemption disabled.
+ */
+static bool rcu_is_callbacks_kthread(struct rcu_data *rdp)
+{
+       return rdp->rcu_cpu_kthread_task == current ||
+                       rcu_is_callbacks_nocb_kthread(rdp);
+}
+
 #ifdef CONFIG_RCU_BOOST
 
 /*
@@ -1151,15 +1170,6 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
        }
 }
 
-/*
- * Is the current CPU running the RCU-callbacks kthread?
- * Caller must have preemption disabled.
- */
-static bool rcu_is_callbacks_kthread(void)
-{
-       return __this_cpu_read(rcu_data.rcu_cpu_kthread_task) == current;
-}
-
 #define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000)
 
 /*
@@ -1242,11 +1252,6 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
        raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 }
 
-static bool rcu_is_callbacks_kthread(void)
-{
-       return false;
-}
-
 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
 {
 }