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Commit 4d3435b8 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Steven Rostedt
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tracing: Change tracing_stats_fops to rely on tracing_get_cpu() 

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

1. Change one of its users, tracing_stats_fops, to use
   tracing_*_generic_tr() instead.

2. Change trace_create_cpu_file("stats", data) to pass "data = tr".

3. Change tracing_stats_read() to use tracing_get_cpu().

Link: http://lkml.kernel.org/r/20130723152603.GA23727@redhat.com



Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 46ef2be0

kernel/trace/trace.c

+6 −7
Original line number Diff line number Diff line
@@ -2982,7 +2982,6 @@ static int tracing_open_generic_tr(struct inode *inode, struct file *filp) 
	filp->private_data = inode->i_private;



	return 0;

	

}



static int tracing_open_generic_tc(struct inode *inode, struct file *filp)
@@ -5285,14 +5284,14 @@ static ssize_t 
tracing_stats_read(struct file *filp, char __user *ubuf,

		   size_t count, loff_t *ppos)

{

	struct trace_cpu *tc = filp->private_data;

	struct trace_array *tr = tc->tr;

	struct inode *inode = file_inode(filp);

	struct trace_array *tr = inode->i_private;

	struct trace_buffer *trace_buf = &tr->trace_buffer;

	int cpu = tracing_get_cpu(inode);

	struct trace_seq *s;

	unsigned long cnt;

	unsigned long long t;

	unsigned long usec_rem;

	int cpu = tc->cpu;



	s = kmalloc(sizeof(*s), GFP_KERNEL);

	if (!s)
@@ -5345,10 +5344,10 @@ tracing_stats_read(struct file *filp, char __user *ubuf, 
}



static const struct file_operations tracing_stats_fops = {

	.open		= tracing_open_generic_tc,

	.open		= tracing_open_generic_tr,

	.read		= tracing_stats_read,

	.llseek		= generic_file_llseek,

	.release	= tracing_release_generic_tc,

	.release	= tracing_release_generic_tr,

};



#ifdef CONFIG_DYNAMIC_FTRACE
@@ -5578,7 +5577,7 @@ tracing_init_debugfs_percpu(struct trace_array *tr, long cpu) 
				tr, cpu, &tracing_buffers_fops);



	trace_create_cpu_file("stats", 0444, d_cpu,

				&data->trace_cpu, cpu, &tracing_stats_fops);

				tr, cpu, &tracing_stats_fops);



	trace_create_cpu_file("buffer_size_kb", 0444, d_cpu,

				&data->trace_cpu, cpu, &tracing_entries_fops);