tracing: Have trace_array keep track if snapshot buffer is allocated

The snapshot buffer belongs to the trace array not the tracer that is
running. The trace array should be the data structure that keeps track
of whether or not the snapshot buffer is allocated, not the tracer
desciptor. Having the trace array keep track of it makes modifications
so much easier.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9bb0b52..bcc9460 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -667,7 +667,7 @@
 
 	WARN_ON_ONCE(!irqs_disabled());
 
-	if (!tr->current_trace->allocated_snapshot) {
+	if (!tr->allocated_snapshot) {
 		/* Only the nop tracer should hit this when disabling */
 		WARN_ON_ONCE(tr->current_trace != &nop_trace);
 		return;
@@ -700,7 +700,7 @@
 		return;
 
 	WARN_ON_ONCE(!irqs_disabled());
-	if (WARN_ON_ONCE(!tr->current_trace->allocated_snapshot))
+	if (WARN_ON_ONCE(!tr->allocated_snapshot))
 		return;
 
 	arch_spin_lock(&ftrace_max_lock);
@@ -802,7 +802,7 @@
 			if (ring_buffer_expanded)
 				ring_buffer_resize(tr->max_buffer.buffer, trace_buf_size,
 						   RING_BUFFER_ALL_CPUS);
-			type->allocated_snapshot = true;
+			tr->allocated_snapshot = true;
 		}
 #endif
 
@@ -822,7 +822,7 @@
 
 #ifdef CONFIG_TRACER_MAX_TRACE
 		if (type->use_max_tr) {
-			type->allocated_snapshot = false;
+			tr->allocated_snapshot = false;
 
 			/* Shrink the max buffer again */
 			if (ring_buffer_expanded)
@@ -2463,7 +2463,7 @@
 
 static void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter)
 {
-	if (iter->trace->allocated_snapshot)
+	if (iter->tr->allocated_snapshot)
 		seq_printf(m, "#\n# * Snapshot is allocated *\n#\n");
 	else
 		seq_printf(m, "#\n# * Snapshot is freed *\n#\n");
@@ -3364,12 +3364,12 @@
 	if (tr->current_trace->reset)
 		tr->current_trace->reset(tr);
 
-#ifdef CONFIG_TRACER_MAX_TRACE
-	had_max_tr = tr->current_trace->allocated_snapshot;
-
 	/* Current trace needs to be nop_trace before synchronize_sched */
 	tr->current_trace = &nop_trace;
 
+#ifdef CONFIG_TRACER_MAX_TRACE
+	had_max_tr = tr->allocated_snapshot;
+
 	if (had_max_tr && !t->use_max_tr) {
 		/*
 		 * We need to make sure that the update_max_tr sees that
@@ -3387,10 +3387,8 @@
 		ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS);
 		set_buffer_entries(&tr->max_buffer, 1);
 		tracing_reset_online_cpus(&tr->max_buffer);
-		tr->current_trace->allocated_snapshot = false;
+		tr->allocated_snapshot = false;
 	}
-#else
-	tr->current_trace = &nop_trace;
 #endif
 	destroy_trace_option_files(topts);
 
@@ -3403,7 +3401,7 @@
 						   RING_BUFFER_ALL_CPUS);
 		if (ret < 0)
 			goto out;
-		t->allocated_snapshot = true;
+		tr->allocated_snapshot = true;
 	}
 #endif
 
@@ -4275,13 +4273,13 @@
 			ret = -EINVAL;
 			break;
 		}
-		if (tr->current_trace->allocated_snapshot) {
+		if (tr->allocated_snapshot) {
 			/* free spare buffer */
 			ring_buffer_resize(tr->max_buffer.buffer, 1,
 					   RING_BUFFER_ALL_CPUS);
 			set_buffer_entries(&tr->max_buffer, 1);
 			tracing_reset_online_cpus(&tr->max_buffer);
-			tr->current_trace->allocated_snapshot = false;
+			tr->allocated_snapshot = false;
 		}
 		break;
 	case 1:
@@ -4292,13 +4290,13 @@
 			break;
 		}
 #endif
-		if (!tr->current_trace->allocated_snapshot) {
+		if (!tr->allocated_snapshot) {
 			/* allocate spare buffer */
 			ret = resize_buffer_duplicate_size(&tr->max_buffer,
 					&tr->trace_buffer, RING_BUFFER_ALL_CPUS);
 			if (ret < 0)
 				break;
-			tr->current_trace->allocated_snapshot = true;
+			tr->allocated_snapshot = true;
 		}
 		local_irq_disable();
 		/* Now, we're going to swap */
@@ -4309,7 +4307,7 @@
 		local_irq_enable();
 		break;
 	default:
-		if (tr->current_trace->allocated_snapshot) {
+		if (tr->allocated_snapshot) {
 			if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
 				tracing_reset_online_cpus(&tr->max_buffer);
 			else
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 986834f..1a456c2 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -197,6 +197,7 @@
 	 * the trace_buffer so the tracing can continue.
 	 */
 	struct trace_buffer	max_buffer;
+	bool			allocated_snapshot;
 #endif
 	int			buffer_disabled;
 	struct trace_cpu	trace_cpu;	/* place holder */
@@ -367,7 +368,6 @@
 	bool			enabled;
 #ifdef CONFIG_TRACER_MAX_TRACE
 	bool			use_max_tr;
-	bool			allocated_snapshot;
 #endif
 };