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authorPaul E. McKenney <paul.mckenney@linaro.org>2011-03-29 17:48:28 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-05-05 23:16:56 -0700
commitd71df90eadfc35aa549ff9a850842673febca71f (patch)
treedd275a3f4848784bc6625574341c11befc1b3823 /kernel/rcutree.c
parent0ac3d136b2e3cdf1161178223bc5da14a06241d0 (diff)
rcu: add tracing for RCU's kthread run states.
Add tracing to help debugging situations when RCU's kthreads are not running but are supposed to be. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcutree.c')
-rw-r--r--kernel/rcutree.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 198e4df7d83..d8917401cbb 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -91,8 +91,9 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active);
* handle all flavors of RCU.
*/
static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task);
+DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
static DEFINE_PER_CPU(wait_queue_head_t, rcu_cpu_wq);
-static DEFINE_PER_CPU(char, rcu_cpu_has_work);
+DEFINE_PER_CPU(char, rcu_cpu_has_work);
static char rcu_kthreads_spawnable;
static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu);
@@ -1563,11 +1564,13 @@ static int rcu_cpu_kthread(void *arg)
int cpu = (int)(long)arg;
unsigned long flags;
int spincnt = 0;
+ unsigned int *statusp = &per_cpu(rcu_cpu_kthread_status, cpu);
wait_queue_head_t *wqp = &per_cpu(rcu_cpu_wq, cpu);
char work;
char *workp = &per_cpu(rcu_cpu_has_work, cpu);
for (;;) {
+ *statusp = RCU_KTHREAD_WAITING;
wait_event_interruptible(*wqp,
*workp != 0 || kthread_should_stop());
local_bh_disable();
@@ -1575,6 +1578,7 @@ static int rcu_cpu_kthread(void *arg)
local_bh_enable();
break;
}
+ *statusp = RCU_KTHREAD_RUNNING;
local_irq_save(flags);
work = *workp;
*workp = 0;
@@ -1587,10 +1591,12 @@ static int rcu_cpu_kthread(void *arg)
else
spincnt = 0;
if (spincnt > 10) {
+ *statusp = RCU_KTHREAD_YIELDING;
rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu);
spincnt = 0;
}
}
+ *statusp = RCU_KTHREAD_STOPPED;
return 0;
}
@@ -1637,10 +1643,12 @@ static int rcu_node_kthread(void *arg)
struct task_struct *t;
for (;;) {
+ rnp->node_kthread_status = RCU_KTHREAD_WAITING;
wait_event_interruptible(rnp->node_wq, rnp->wakemask != 0 ||
kthread_should_stop());
if (kthread_should_stop())
break;
+ rnp->node_kthread_status = RCU_KTHREAD_RUNNING;
raw_spin_lock_irqsave(&rnp->lock, flags);
mask = rnp->wakemask;
rnp->wakemask = 0;
@@ -1661,6 +1669,7 @@ static int rcu_node_kthread(void *arg)
preempt_enable();
}
}
+ rnp->node_kthread_status = RCU_KTHREAD_STOPPED;
return 0;
}