Commit 53ab6680 authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar
Browse files

ksym_tracer: Remove trace_stat 



trace_stat is problematic. Don't use it, use seqfile instead.

This fixes a race that reading the stat file is not protected by
any lock, which can lead to use after free.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4B3AF203.40200@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e6d9491b

kernel/trace/trace_ksym.c

+50 −77
Original line number Diff line number Diff line
@@ -26,7 +26,6 @@ 
#include <linux/fs.h>



#include "trace_output.h"

#include "trace_stat.h"

#include "trace.h"



#include <linux/hw_breakpoint.h>
@@ -444,43 +443,21 @@ struct tracer ksym_tracer __read_mostly = 
	.print_line	= ksym_trace_output

};



__init static int init_ksym_trace(void)

{

	struct dentry *d_tracer;

	struct dentry *entry;



	d_tracer = tracing_init_dentry();

	ksym_filter_entry_count = 0;



	entry = debugfs_create_file("ksym_trace_filter", 0644, d_tracer,

				    NULL, &ksym_tracing_fops);

	if (!entry)

		pr_warning("Could not create debugfs "

			   "'ksym_trace_filter' file\n");



	return register_tracer(&ksym_tracer);

}

device_initcall(init_ksym_trace);





#ifdef CONFIG_PROFILE_KSYM_TRACER

static int ksym_tracer_stat_headers(struct seq_file *m)

static int ksym_profile_show(struct seq_file *m, void *v)

{

	struct hlist_node *node;

	struct trace_ksym *entry;

	int access_type = 0;

	char fn_name[KSYM_NAME_LEN];



	seq_puts(m, "  Access Type ");

	seq_puts(m, "  Symbol                                       Counter\n");

	seq_puts(m, "  ----------- ");

	seq_puts(m, "  ------                                       -------\n");

	return 0;

}



static int ksym_tracer_stat_show(struct seq_file *m, void *v)

{

	struct hlist_node *stat = v;

	struct trace_ksym *entry;

	int access_type = 0;

	char fn_name[KSYM_NAME_LEN];



	entry = hlist_entry(stat, struct trace_ksym, ksym_hlist);

	rcu_read_lock();

	hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) {



		access_type = entry->attr.bp_type;
@@ -504,43 +481,39 @@ static int ksym_tracer_stat_show(struct seq_file *m, void *v) 
			seq_printf(m, "  %-36s", "<NA>");

		seq_printf(m, " %15llu\n",

			   (unsigned long long)atomic64_read(&entry->counter));



	return 0;

	}

	rcu_read_unlock();



static void *ksym_tracer_stat_start(struct tracer_stat *trace)

{

	return ksym_filter_head.first;

	return 0;

}



static void *

ksym_tracer_stat_next(void *v, int idx)

static int ksym_profile_open(struct inode *node, struct file *file)

{

	struct hlist_node *stat = v;



	return stat->next;

	return single_open(file, ksym_profile_show, NULL);

}



static struct tracer_stat ksym_tracer_stats = {

	.name = "ksym_tracer",

	.stat_start = ksym_tracer_stat_start,

	.stat_next = ksym_tracer_stat_next,

	.stat_headers = ksym_tracer_stat_headers,

	.stat_show = ksym_tracer_stat_show

static const struct file_operations ksym_profile_fops = {

	.open		= ksym_profile_open,

	.read		= seq_read,

	.llseek		= seq_lseek,

	.release	= single_release,

};

#endif /* CONFIG_PROFILE_KSYM_TRACER */



__init static int ksym_tracer_stat_init(void)

__init static int init_ksym_trace(void)

{

	int ret;

	struct dentry *d_tracer;



	ret = register_stat_tracer(&ksym_tracer_stats);

	if (ret) {

		printk(KERN_WARNING "Warning: could not register "

				    "ksym tracer stats\n");

		return 1;

	}

	d_tracer = tracing_init_dentry();



	return 0;

	trace_create_file("ksym_trace_filter", 0644, d_tracer,

			  NULL, &ksym_tracing_fops);



#ifdef CONFIG_PROFILE_KSYM_TRACER

	trace_create_file("ksym_profile", 0444, d_tracer,

			  NULL, &ksym_profile_fops);

#endif



	return register_tracer(&ksym_tracer);

}

fs_initcall(ksym_tracer_stat_init);

#endif /* CONFIG_PROFILE_KSYM_TRACER */
 
device_initcall(init_ksym_trace);

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