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authorFlorian Westphal <fw@strlen.de>2016-08-11 15:17:55 +0200
committerSteffen Klassert <steffen.klassert@secunet.com>2016-08-12 08:07:11 +0200
commite37cc8ade5afaf082f804c6d18eb23377146bec4 (patch)
treec9e1bf67bfedc04fb6e0b6840bd280198c300549 /net/xfrm
parent30846090a746edfdb230deadd638cfa96f7b8c91 (diff)
downloadlinux-e37cc8ade5afaf082f804c6d18eb23377146bec4.tar.bz2
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>
Diffstat (limited to 'net/xfrm')
-rw-r--r--net/xfrm/xfrm_policy.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 576d90321068..09f2e2b38246 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -60,6 +60,11 @@ static void __xfrm_policy_link(struct xfrm_policy *pol, int dir);
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 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type,
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);