xfrm: policy: use atomic_inc_not_zero in rcu section
If we don't hold the policy lock anymore the refcnt might
already be 0, i.e. policy struct is about to be free'd.
Switch to atomic_inc_not_zero to avoid this.
On removal policies are already unlinked from the tables (lists)
before the last _put occurs so we are not supposed to find the same
'dead' entry on the next loop, so its safe to just repeat the lookup.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 576d903..09f2e2b 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -60,6 +60,11 @@
static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
int dir);
+static inline bool xfrm_pol_hold_rcu(struct xfrm_policy *policy)
+{
+ return atomic_inc_not_zero(&policy->refcnt);
+}
+
static inline bool
__xfrm4_selector_match(const struct xfrm_selector *sel, const struct flowi *fl)
{
@@ -1164,7 +1169,8 @@
if (read_seqcount_retry(&xfrm_policy_hash_generation, sequence))
goto retry;
- xfrm_pol_hold(ret);
+ if (ret && !xfrm_pol_hold_rcu(ret))
+ goto retry;
fail:
read_unlock_bh(&net->xfrm.xfrm_policy_lock);