---

yaml
---
r: 268978
b: refs/heads/master
c: 9bc8b55
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 037067a1b6f9a70f862f3ed9d59fe28b7cd55ac4
+refs/heads/master: 9bc8b5586f94be6391458074ecbba8827ba8ba9d

trunk/kernel/rcutree.c

@@ -545,6 +545,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
 	int cpu;
 	long delta;
 	unsigned long flags;
+	int ndetected;
 	struct rcu_node *rnp = rcu_get_root(rsp);
 
 	/* Only let one CPU complain about others per time interval. */
@@ -561,7 +562,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
 	 * Now rat on any tasks that got kicked up to the root rcu_node
 	 * due to CPU offlining.
 	 */
-	rcu_print_task_stall(rnp);
+	ndetected = rcu_print_task_stall(rnp);
 	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 
 	/*
@@ -573,17 +574,21 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
 	       rsp->name);
 	rcu_for_each_leaf_node(rsp, rnp) {
 		raw_spin_lock_irqsave(&rnp->lock, flags);
-		rcu_print_task_stall(rnp);
+		ndetected += rcu_print_task_stall(rnp);
 		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 		if (rnp->qsmask == 0)
 			continue;
 		for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
-			if (rnp->qsmask & (1UL << cpu))
+			if (rnp->qsmask & (1UL << cpu)) {
 				printk(" %d", rnp->grplo + cpu);
+				ndetected++;
+			}
 	}
 	printk("} (detected by %d, t=%ld jiffies)\n",
 	       smp_processor_id(), (long)(jiffies - rsp->gp_start));
-	if (!trigger_all_cpu_backtrace())
+	if (ndetected == 0)
+		printk(KERN_ERR "INFO: Stall ended before state dump start\n");
+	else if (!trigger_all_cpu_backtrace())
 		dump_stack();
 
 	/* If so configured, complain about tasks blocking the grace period. */

trunk/kernel/rcutree.h

@@ -438,7 +438,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
 static void rcu_stop_cpu_kthread(int cpu);
 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
-static void rcu_print_task_stall(struct rcu_node *rnp);
+static int rcu_print_task_stall(struct rcu_node *rnp);
 static void rcu_preempt_stall_reset(void);
 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
 #ifdef CONFIG_HOTPLUG_CPU

trunk/kernel/rcutree_plugin.h

@@ -483,16 +483,20 @@ static void rcu_print_detail_task_stall(struct rcu_state *rsp)
  * Scan the current list of tasks blocked within RCU read-side critical
  * sections, printing out the tid of each.
  */
-static void rcu_print_task_stall(struct rcu_node *rnp)
+static int rcu_print_task_stall(struct rcu_node *rnp)
 {
 	struct task_struct *t;
+	int ndetected = 0;
 
 	if (!rcu_preempt_blocked_readers_cgp(rnp))
-		return;
+		return 0;
 	t = list_entry(rnp->gp_tasks,
 		       struct task_struct, rcu_node_entry);
-	list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry)
+	list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) {
 		printk(" P%d", t->pid);
+		ndetected++;
+	}
+	return ndetected;
 }
 
 /*
@@ -976,8 +980,9 @@ static void rcu_print_detail_task_stall(struct rcu_state *rsp)
  * Because preemptible RCU does not exist, we never have to check for
  * tasks blocked within RCU read-side critical sections.
  */
-static void rcu_print_task_stall(struct rcu_node *rnp)
+static int rcu_print_task_stall(struct rcu_node *rnp)
 {
+	return 0;
 }
 
 /*