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ftrace: safe traversal of ftrace_hash hlist

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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>
This commit is contained in:
Abhishek Sagar 2008-05-24 23:45:02 +05:30 committed by Thomas Gleixner
parent ccbfac2923
commit ffdaa3582b
1 changed files with 2 additions and 2 deletions
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4
kernel/trace/ftrace.c
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@ -201,7 +201,7 @@ ftrace_ip_in_hash(unsigned long ip, unsigned long key)
struct hlist_node *t; struct hlist_node *t;
int found = 0; 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) { if (p->ip == ip) {
found = 1; found = 1;
break; break;
@ -214,7 +214,7 @@ ftrace_ip_in_hash(unsigned long ip, unsigned long key)
static inline void static inline void
ftrace_add_hash(struct dyn_ftrace *node, unsigned long key) 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) static void ftrace_free_rec(struct dyn_ftrace *rec)