Commit ffdaa358 authored by Abhishek Sagar's avatar Abhishek Sagar Committed by Thomas Gleixner
Browse files

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: default avatarAbhishek Sagar <>
Signed-off-by: default avatarThomas Gleixner <>
parent ccbfac29
......@@ -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;
......@@ -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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