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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 <sagar.abhishek@gmail.com>
Cc: rostedt@goodmis.org
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent ccbfac29

kernel/trace/ftrace.c

+2 −2
Original line number Diff line number Diff line
@@ -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)