Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9457158b authored by Alexander Z Lam's avatar Alexander Z Lam Committed by Steven Rostedt
Browse files

tracing: Fix reset of time stamps during trace_clock changes 

Fixed two issues with changing the timestamp clock with trace_clock:

 - The global buffer was reset on instance clock changes. Change this to pass
   the correct per-instance buffer
 - ftrace_now() is used to set buf->time_start in tracing_reset_online_cpus().
   This was incorrect because ftrace_now() used the global buffer's clock to
   return the current time. Change this to use buffer_ftrace_now() which
   returns the current time for the correct per-instance buffer.

Also removed tracing_reset_current() because it is not used anywhere

Link: http://lkml.kernel.org/r/1375493777-17261-2-git-send-email-azl@google.com



Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Cc: stable@vger.kernel.org # 3.10
Signed-off-by: default avatarAlexander Z Lam <azl@google.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 711e1243

kernel/trace/trace.c

+12 −12
Original line number Diff line number Diff line
@@ -243,20 +243,25 @@ int filter_current_check_discard(struct ring_buffer *buffer, 
}

EXPORT_SYMBOL_GPL(filter_current_check_discard);



cycle_t ftrace_now(int cpu)

cycle_t buffer_ftrace_now(struct trace_buffer *buf, int cpu)

{

	u64 ts;



	/* Early boot up does not have a buffer yet */

	if (!global_trace.trace_buffer.buffer)

	if (!buf->buffer)

		return trace_clock_local();



	ts = ring_buffer_time_stamp(global_trace.trace_buffer.buffer, cpu);

	ring_buffer_normalize_time_stamp(global_trace.trace_buffer.buffer, cpu, &ts);

	ts = ring_buffer_time_stamp(buf->buffer, cpu);

	ring_buffer_normalize_time_stamp(buf->buffer, cpu, &ts);



	return ts;

}



cycle_t ftrace_now(int cpu)

{

	return buffer_ftrace_now(&global_trace.trace_buffer, cpu);

}



/**

 * tracing_is_enabled - Show if global_trace has been disabled

 *
@@ -1211,7 +1216,7 @@ void tracing_reset_online_cpus(struct trace_buffer *buf) 
	/* Make sure all commits have finished */

	synchronize_sched();



	buf->time_start = ftrace_now(buf->cpu);

	buf->time_start = buffer_ftrace_now(buf, buf->cpu);



	for_each_online_cpu(cpu)

		ring_buffer_reset_cpu(buffer, cpu);
@@ -1219,11 +1224,6 @@ void tracing_reset_online_cpus(struct trace_buffer *buf) 
	ring_buffer_record_enable(buffer);

}



void tracing_reset_current(int cpu)

{

	tracing_reset(&global_trace.trace_buffer, cpu);

}



/* Must have trace_types_lock held */

void tracing_reset_all_online_cpus(void)

{
@@ -4634,12 +4634,12 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf, 
	 * New clock may not be consistent with the previous clock.

	 * Reset the buffer so that it doesn't have incomparable timestamps.

	 */

	tracing_reset_online_cpus(&global_trace.trace_buffer);

	tracing_reset_online_cpus(&tr->trace_buffer);



#ifdef CONFIG_TRACER_MAX_TRACE

	if (tr->flags & TRACE_ARRAY_FL_GLOBAL && tr->max_buffer.buffer)

		ring_buffer_set_clock(tr->max_buffer.buffer, trace_clocks[i].func);

	tracing_reset_online_cpus(&global_trace.max_buffer);

	tracing_reset_online_cpus(&tr->max_buffer);

#endif



	mutex_unlock(&trace_types_lock);