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Subject[for-next-3.11][PATCH 3/9] tracing: Change tracing_buffers_fops to rely on tracing_get_cpu()
From: Oleg Nesterov <oleg@redhat.com>

tracing_buffers_open() is racy, the memory inode->i_private points
to can be already freed.

Change debugfs_create_file("trace_pipe_raw", data) caller to pass
"data = tr", tracing_buffers_open() can use tracing_get_cpu().

Change debugfs_create_file("snapshot_raw_fops", data) caller too,
this file uses tracing_buffers_open/release.

Link: http://lkml.kernel.org/r/20130723152600.GA23720@redhat.com

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 51a99ef..30c058a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4949,8 +4949,7 @@ static const struct file_operations snapshot_raw_fops = {

static int tracing_buffers_open(struct inode *inode, struct file *filp)
{
- struct trace_cpu *tc = inode->i_private;
- struct trace_array *tr = tc->tr;
+ struct trace_array *tr = inode->i_private;
struct ftrace_buffer_info *info;
int ret;

@@ -4969,7 +4968,7 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
mutex_lock(&trace_types_lock);

info->iter.tr = tr;
- info->iter.cpu_file = tc->cpu;
+ info->iter.cpu_file = tracing_get_cpu(inode);
info->iter.trace = tr->current_trace;
info->iter.trace_buffer = &tr->trace_buffer;
info->spare = NULL;
@@ -5576,7 +5575,7 @@ tracing_init_debugfs_percpu(struct trace_array *tr, long cpu)
&data->trace_cpu, cpu, &tracing_fops);

trace_create_cpu_file("trace_pipe_raw", 0444, d_cpu,
- &data->trace_cpu, cpu, &tracing_buffers_fops);
+ tr, cpu, &tracing_buffers_fops);

trace_create_cpu_file("stats", 0444, d_cpu,
&data->trace_cpu, cpu, &tracing_stats_fops);
@@ -5589,7 +5588,7 @@ tracing_init_debugfs_percpu(struct trace_array *tr, long cpu)
&data->trace_cpu, cpu, &snapshot_fops);

trace_create_cpu_file("snapshot_raw", 0444, d_cpu,
- &data->trace_cpu, cpu, &snapshot_raw_fops);
+ tr, cpu, &snapshot_raw_fops);
#endif
}

--
1.7.10.4



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