---

yaml
---
r: 146033
b: refs/heads/master
c: 261842b
h: refs/heads/master
i:
  146031: 86a1a24
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 12acd473d45cf2e40de3782cb2de712e5cd4d715
+refs/heads/master: 261842b7c9099f56de2eb969c8ad65402d68e00e

trunk/include/linux/ftrace.h

@@ -488,8 +488,15 @@ static inline int test_tsk_trace_graph(struct task_struct *tsk)
 
 extern int ftrace_dump_on_oops;
 
+#ifdef CONFIG_PREEMPT
+#define INIT_TRACE_RECURSION		.trace_recursion = 0,
+#endif
+
 #endif /* CONFIG_TRACING */
 
+#ifndef INIT_TRACE_RECURSION
+#define INIT_TRACE_RECURSION
+#endif
 
 #ifdef CONFIG_HW_BRANCH_TRACER
 

trunk/include/linux/init_task.h

@@ -187,6 +187,7 @@ extern struct cred init_cred;
 	INIT_TRACE_IRQFLAGS						\
 	INIT_LOCKDEP							\
 	INIT_FTRACE_GRAPH						\
+	INIT_TRACE_RECURSION						\
 }
 
 

trunk/include/linux/sched.h

@@ -1428,7 +1428,9 @@ struct task_struct {
 #ifdef CONFIG_TRACING
 	/* state flags for use by tracers */
 	unsigned long trace;
-#endif
+	/* bitmask of trace recursion */
+	unsigned long trace_recursion;
+#endif /* CONFIG_TRACING */
 };
 
 /* Future-safe accessor for struct task_struct's cpus_allowed. */

trunk/kernel/trace/ring_buffer.c

@@ -1481,6 +1481,40 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
 	return event;
 }
 
+static int trace_irq_level(void)
+{
+	return hardirq_count() + softirq_count() + in_nmi();
+}
+
+static int trace_recursive_lock(void)
+{
+	int level;
+
+	level = trace_irq_level();
+
+	if (unlikely(current->trace_recursion & (1 << level))) {
+		/* Disable all tracing before we do anything else */
+		tracing_off_permanent();
+		WARN_ON_ONCE(1);
+		return -1;
+	}
+
+	current->trace_recursion |= 1 << level;
+
+	return 0;
+}
+
+static void trace_recursive_unlock(void)
+{
+	int level;
+
+	level = trace_irq_level();
+
+	WARN_ON_ONCE(!current->trace_recursion & (1 << level));
+
+	current->trace_recursion &= ~(1 << level);
+}
+
 static DEFINE_PER_CPU(int, rb_need_resched);
 
 /**
@@ -1514,6 +1548,9 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length)
 	/* If we are tracing schedule, we don't want to recurse */
 	resched = ftrace_preempt_disable();
 
+	if (trace_recursive_lock())
+		goto out_nocheck;
+
 	cpu = raw_smp_processor_id();
 
 	if (!cpumask_test_cpu(cpu, buffer->cpumask))
@@ -1543,6 +1580,9 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length)
 	return event;
 
  out:
+	trace_recursive_unlock();
+
+ out_nocheck:
 	ftrace_preempt_enable(resched);
 	return NULL;
 }
@@ -1581,6 +1621,8 @@ int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 
 	rb_commit(cpu_buffer, event);
 
+	trace_recursive_unlock();
+
 	/*
 	 * Only the last preempt count needs to restore preemption.
 	 */