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-rw-r--r--kernel/rcutree.c13
-rw-r--r--kernel/rcutree.h2
-rw-r--r--kernel/rcutree_plugin.h13
3 files changed, 19 insertions, 9 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 9970116163b..ade788320dd 100644
--- a/kernel/rcutree.c
+++ b/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. */
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 51638b68b2d..f509f728f9f 100644
--- a/kernel/rcutree.h
+++ b/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
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index eeb38ee8ebb..d3127e8764c 100644
--- a/kernel/rcutree_plugin.h
+++ b/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;
}
/*