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authorIngo Molnar <mingo@elte.hu>2008-05-12 21:20:52 +0200
committerThomas Gleixner <tglx@linutronix.de>2008-05-23 21:05:02 +0200
commit017730c11241e26577673eb9d957cfc66172ea91 (patch)
tree3585323be944d23814b3e28b50042b7477cc9206
parent24cd5d111e8c713e62cda7ca1d01232402e3d3c9 (diff)
downloadop-kernel-dev-017730c11241e26577673eb9d957cfc66172ea91.zip
op-kernel-dev-017730c11241e26577673eb9d957cfc66172ea91.tar.gz
ftrace: fix wakeups
Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--include/linux/sched.h2
-rw-r--r--kernel/sched.c18
-rw-r--r--kernel/trace/trace.c15
3 files changed, 31 insertions, 4 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 652d380..a3970b5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -246,6 +246,8 @@ extern asmlinkage void schedule_tail(struct task_struct *prev);
extern void init_idle(struct task_struct *idle, int cpu);
extern void init_idle_bootup_task(struct task_struct *idle);
+extern int runqueue_is_locked(void);
+
extern cpumask_t nohz_cpu_mask;
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ)
extern int select_nohz_load_balancer(int cpu);
diff --git a/kernel/sched.c b/kernel/sched.c
index 673b588..9ca4a2e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -642,6 +642,24 @@ static inline void update_rq_clock(struct rq *rq)
# define const_debug static const
#endif
+/**
+ * runqueue_is_locked
+ *
+ * Returns true if the current cpu runqueue is locked.
+ * This interface allows printk to be called with the runqueue lock
+ * held and know whether or not it is OK to wake up the klogd.
+ */
+int runqueue_is_locked(void)
+{
+ int cpu = get_cpu();
+ struct rq *rq = cpu_rq(cpu);
+ int ret;
+
+ ret = spin_is_locked(&rq->lock);
+ put_cpu();
+ return ret;
+}
+
/*
* Debugging: various feature bits
*/
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 65173b1..2ca9d66 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -70,12 +70,13 @@ static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
unsigned long trace_flags = TRACE_ITER_PRINT_PARENT;
-/*
- * FIXME: where should this be called?
- */
void trace_wake_up(void)
{
- if (!(trace_flags & TRACE_ITER_BLOCK))
+ /*
+ * The runqueue_is_locked() can fail, but this is the best we
+ * have for now:
+ */
+ if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
wake_up(&trace_wait);
}
@@ -657,6 +658,8 @@ trace_function(struct trace_array *tr, struct trace_array_cpu *data,
entry->fn.ip = ip;
entry->fn.parent_ip = parent_ip;
spin_unlock_irqrestore(&data->lock, irq_flags);
+
+ trace_wake_up();
}
void
@@ -686,6 +689,8 @@ __trace_special(void *__tr, void *__data,
entry->special.arg2 = arg2;
entry->special.arg3 = arg3;
spin_unlock_irqrestore(&data->lock, irq_flags);
+
+ trace_wake_up();
}
#endif
@@ -759,6 +764,8 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
entry->ctx.next_prio = wakee->prio;
__trace_stack(tr, data, flags, 5);
spin_unlock_irqrestore(&data->lock, irq_flags);
+
+ trace_wake_up();
}
#ifdef CONFIG_FTRACE
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