lkml.org 
[lkml]   [2012]   [Apr]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 2/2] tracing: Fix regression with tracing_on
From: Steven Rostedt <srostedt@redhat.com>

The change to make tracing_on affect only the ftrace ring buffer, caused
a bug where it wont affect any ring buffer. The problem was that the buffer
of the trace_array was passed to the write function and not the trace array
itself.

The trace_array can change the buffer when running a latency tracer. If this
happens, then the buffer being disabled may not be the buffer currently used
by ftrace. This will cause the tracing_on file to become useless.

The simple fix is to pass the trace_array to the write function instead of
the buffer. Then the actual buffer may be changed.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ed7b5d1..2a22255 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4629,7 +4629,8 @@ static ssize_t
rb_simple_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
- struct ring_buffer *buffer = filp->private_data;
+ struct trace_array *tr = filp->private_data;
+ struct ring_buffer *buffer = tr->buffer;
char buf[64];
int r;

@@ -4647,7 +4648,8 @@ static ssize_t
rb_simple_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
- struct ring_buffer *buffer = filp->private_data;
+ struct trace_array *tr = filp->private_data;
+ struct ring_buffer *buffer = tr->buffer;
unsigned long val;
int ret;

@@ -4734,7 +4736,7 @@ static __init int tracer_init_debugfs(void)
&trace_clock_fops);

trace_create_file("tracing_on", 0644, d_tracer,
- global_trace.buffer, &rb_simple_fops);
+ &global_trace, &rb_simple_fops);

#ifdef CONFIG_DYNAMIC_FTRACE
trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
--
1.7.9.5

[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2012-04-18 22:37    [W:0.055 / U:0.188 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site