From ffdaa3582b6b39d625d585d07e329ffdc925e971 Mon Sep 17 00:00:00 2001
From: Abhishek Sagar <sagar.abhishek@gmail.com>
Date: Sat, 24 May 2008 23:45:02 +0530
Subject: [PATCH] ftrace: safe traversal of ftrace_hash hlist
Hi Steven,
I noticed that concurrent instances of ftrace_record_ip()
have a race between ftrace_hash list traversal during
ftrace_ip_in_hash() (before acquiring ftrace_shutdown_lock)
and ftrace_add_hash(). If it's so then this should fix it.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: rostedt@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/trace/ftrace.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 2552454609cf..9b7c54f8a62f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -201,7 +201,7 @@ ftrace_ip_in_hash(unsigned long ip, unsigned long key)
struct hlist_node *t;
int found = 0;
- hlist_for_each_entry(p, t, &ftrace_hash[key], node) {
+ hlist_for_each_entry_rcu(p, t, &ftrace_hash[key], node) {
if (p->ip == ip) {
found = 1;
break;
@@ -214,7 +214,7 @@ ftrace_ip_in_hash(unsigned long ip, unsigned long key)
static inline void
ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
{
- hlist_add_head(&node->node, &ftrace_hash[key]);
+ hlist_add_head_rcu(&node->node, &ftrace_hash[key]);
}
static void ftrace_free_rec(struct dyn_ftrace *rec)
--
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