tracing: Consolidate max_tr into main trace_array structure

Currently, the way the latency tracers and snapshot feature works
is to have a separate trace_array called "max_tr" that holds the
snapshot buffer. For latency tracers, this snapshot buffer is used
to swap the running buffer with this buffer to save the current max
latency.

The only items needed for the max_tr is really just a copy of the buffer
itself, the per_cpu data pointers, the time_start timestamp that states
when the max latency was triggered, and the cpu that the max latency
was triggered on. All other fields in trace_array are unused by the
max_tr, making the max_tr mostly bloat.

This change removes the max_tr completely, and adds a new structure
called trace_buffer, that holds the buffer pointer, the per_cpu data
pointers, the time_start timestamp, and the cpu where the latency occurred.

The trace_array, now has two trace_buffers, one for the normal trace and
one for the max trace or snapshot. By doing this, not only do we remove
the bloat from the max_trace but the instances of traces can now use
their own snapshot feature and not have just the top level global_trace have
the snapshot feature and latency tracers for itself.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 21 insertions, 21 deletions

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 51c819c..8672c40 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -21,13 +21,13 @@ static inline int trace_valid_entry(struct trace_entry *entry)
 	return 0;
 }
 
-static int trace_test_buffer_cpu(struct trace_array *tr, int cpu)
+static int trace_test_buffer_cpu(struct trace_buffer *buf, int cpu)
 {
 	struct ring_buffer_event *event;
 	struct trace_entry *entry;
 	unsigned int loops = 0;
 
-	while ((event = ring_buffer_consume(tr->buffer, cpu, NULL, NULL))) {
+	while ((event = ring_buffer_consume(buf->buffer, cpu, NULL, NULL))) {
 		entry = ring_buffer_event_data(event);
 
 		/*
@@ -58,7 +58,7 @@ static int trace_test_buffer_cpu(struct trace_array *tr, int cpu)
  * Test the trace buffer to see if all the elements
  * are still sane.
  */
-static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
+static int trace_test_buffer(struct trace_buffer *buf, unsigned long *count)
 {
 	unsigned long flags, cnt = 0;
 	int cpu, ret = 0;
@@ -67,7 +67,7 @@ static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
 	local_irq_save(flags);
 	arch_spin_lock(&ftrace_max_lock);
 
-	cnt = ring_buffer_entries(tr->buffer);
+	cnt = ring_buffer_entries(buf->buffer);
 
 	/*
 	 * The trace_test_buffer_cpu runs a while loop to consume all data.
@@ -78,7 +78,7 @@ static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
 	 */
 	tracing_off();
 	for_each_possible_cpu(cpu) {
-		ret = trace_test_buffer_cpu(tr, cpu);
+		ret = trace_test_buffer_cpu(buf, cpu);
 		if (ret)
 			break;
 	}
@@ -355,7 +355,7 @@ int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
 	msleep(100);
 
 	/* we should have nothing in the buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 	if (ret)
 		goto out;
 
@@ -376,7 +376,7 @@ int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
 	ftrace_enabled = 0;
 
 	/* check the trace buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 	tracing_start();
 
 	/* we should only have one item */
@@ -666,7 +666,7 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
 	ftrace_enabled = 0;
 
 	/* check the trace buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 	trace->reset(tr);
 	tracing_start();
 
@@ -737,7 +737,7 @@ trace_selftest_startup_function_graph(struct tracer *trace,
 	 * Simulate the init() callback but we attach a watchdog callback
 	 * to detect and recover from possible hangs
 	 */
-	tracing_reset_online_cpus(tr);
+	tracing_reset_online_cpus(&tr->trace_buffer);
 	set_graph_array(tr);
 	ret = register_ftrace_graph(&trace_graph_return,
 				    &trace_graph_entry_watchdog);
@@ -760,7 +760,7 @@ trace_selftest_startup_function_graph(struct tracer *trace,
 	tracing_stop();
 
 	/* check the trace buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 
 	trace->reset(tr);
 	tracing_start();
@@ -815,9 +815,9 @@ trace_selftest_startup_irqsoff(struct tracer *trace, struct trace_array *tr)
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	if (!ret)
-		ret = trace_test_buffer(&max_tr, &count);
+		ret = trace_test_buffer(&tr->max_buffer, &count);
 	trace->reset(tr);
 	tracing_start();
 
@@ -877,9 +877,9 @@ trace_selftest_startup_preemptoff(struct tracer *trace, struct trace_array *tr)
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	if (!ret)
-		ret = trace_test_buffer(&max_tr, &count);
+		ret = trace_test_buffer(&tr->max_buffer, &count);
 	trace->reset(tr);
 	tracing_start();
 
@@ -943,11 +943,11 @@ trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	if (ret)
 		goto out;
 
-	ret = trace_test_buffer(&max_tr, &count);
+	ret = trace_test_buffer(&tr->max_buffer, &count);
 	if (ret)
 		goto out;
 
@@ -973,11 +973,11 @@ trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	if (ret)
 		goto out;
 
-	ret = trace_test_buffer(&max_tr, &count);
+	ret = trace_test_buffer(&tr->max_buffer, &count);
 
 	if (!ret && !count) {
 		printk(KERN_CONT ".. no entries found ..");
@@ -1084,10 +1084,10 @@ trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	printk("ret = %d\n", ret);
 	if (!ret)
-		ret = trace_test_buffer(&max_tr, &count);
+		ret = trace_test_buffer(&tr->max_buffer, &count);
 
 
 	trace->reset(tr);
@@ -1126,7 +1126,7 @@ trace_selftest_startup_sched_switch(struct tracer *trace, struct trace_array *tr
 	/* stop the tracing. */
 	tracing_stop();
 	/* check the trace buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 	trace->reset(tr);
 	tracing_start();