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Date: Wed, 30 Dec 2009 14:24:03 +0800
From: Li Zefan <lizf@...fujitsu.com>
To: Frederic Weisbecker <fweisbec@...il.com>
CC: Steven Rostedt <rostedt@...dmis.org>, Ingo Molnar <mingo@...e.hu>,
"K.Prasad" <prasad@...ux.vnet.ibm.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 4/4] 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: Li Zefan <lizf@...fujitsu.com>
---
kernel/trace/trace_ksym.c | 127 ++++++++++++++++++---------------------------
1 files changed, 50 insertions(+), 77 deletions(-)
diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index 67d79f7..94103cd 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -26,7 +26,6 @@
#include <linux/fs.h>
#include "trace_output.h"
-#include "trace_stat.h"
#include "trace.h"
#include <linux/hw_breakpoint.h>
@@ -444,103 +443,77 @@ 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];
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) {
- entry = hlist_entry(stat, struct trace_ksym, ksym_hlist);
+ access_type = entry->attr.bp_type;
- access_type = entry->attr.bp_type;
+ switch (access_type) {
+ case HW_BREAKPOINT_R:
+ seq_puts(m, " R ");
+ break;
+ case HW_BREAKPOINT_W:
+ seq_puts(m, " W ");
+ break;
+ case HW_BREAKPOINT_R | HW_BREAKPOINT_W:
+ seq_puts(m, " RW ");
+ break;
+ default:
+ seq_puts(m, " NA ");
+ }
- switch (access_type) {
- case HW_BREAKPOINT_R:
- seq_puts(m, " R ");
- break;
- case HW_BREAKPOINT_W:
- seq_puts(m, " W ");
- break;
- case HW_BREAKPOINT_R | HW_BREAKPOINT_W:
- seq_puts(m, " RW ");
- break;
- default:
- seq_puts(m, " NA ");
+ if (lookup_symbol_name(entry->attr.bp_addr, fn_name) >= 0)
+ seq_printf(m, " %-36s", fn_name);
+ else
+ seq_printf(m, " %-36s", "<NA>");
+ seq_printf(m, " %15llu\n",
+ (unsigned long long)atomic64_read(&entry->counter));
}
-
- if (lookup_symbol_name(entry->attr.bp_addr, fn_name) >= 0)
- seq_printf(m, " %-36s", fn_name);
- else
- seq_printf(m, " %-36s", "<NA>");
- seq_printf(m, " %15llu\n",
- (unsigned long long)atomic64_read(&entry->counter));
+ rcu_read_unlock();
return 0;
}
-static void *ksym_tracer_stat_start(struct tracer_stat *trace)
+static int ksym_profile_open(struct inode *node, struct file *file)
{
- return ksym_filter_head.first;
-}
-
-static void *
-ksym_tracer_stat_next(void *v, int idx)
-{
- 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);
-- 1.6.3
--
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