From: Steffen Klassert <steffen.klassert@secunet.com>
To: David Miller <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
Steffen Klassert <steffen.klassert@secunet.com>,
<netdev@vger.kernel.org>
Subject: [PATCH 11/17] xfrm: policy: use atomic_inc_not_zero in rcu section
Date: Thu, 8 Sep 2016 07:54:46 +0200 [thread overview]
Message-ID: <1473314092-11319-12-git-send-email-steffen.klassert@secunet.com> (raw)
In-Reply-To: <1473314092-11319-1-git-send-email-steffen.klassert@secunet.com>
From: Florian Westphal <fw@strlen.de>
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>
---
net/xfrm/xfrm_policy.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
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 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);
--
1.9.1
next prev parent reply other threads:[~2016-09-08 6:51 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-08 5:54 pull request (net-next): ipsec-next 2016-09-08 Steffen Klassert
2016-09-08 5:54 ` [PATCH 01/17] xfrm: constify xfrm_replay structures Steffen Klassert
2016-09-08 5:54 ` [PATCH 02/17] xfrm: state: use hlist_for_each_entry_rcu helper Steffen Klassert
2016-09-08 5:54 ` [PATCH 03/17] xfrm: state: use atomic_inc_not_zero to increment refcount Steffen Klassert
2016-09-08 5:54 ` [PATCH 04/17] xfrm: state: delay freeing until rcu grace period has elapsed Steffen Klassert
2016-09-08 5:54 ` [PATCH 05/17] xfrm: state: add sequence count to detect hash resizes Steffen Klassert
2016-09-08 5:54 ` [PATCH 06/17] xfrm: state: use rcu_deref and assign_pointer helpers Steffen Klassert
2016-09-08 5:54 ` [PATCH 07/17] xfrm: state: don't use lock anymore unless acquire operation is needed Steffen Klassert
2016-09-08 5:54 ` [PATCH 08/17] xfrm: policy: use rcu versions for iteration and list add/del Steffen Klassert
2016-09-08 5:54 ` [PATCH 09/17] xfrm: policy: prepare policy_bydst hash for rcu lookups Steffen Klassert
2016-09-08 5:54 ` [PATCH 10/17] xfrm: policy: add sequence count to sync with hash resize Steffen Klassert
2016-09-08 5:54 ` Steffen Klassert [this message]
2016-09-08 5:54 ` [PATCH 12/17] xfrm: policy: make xfrm_policy_lookup_bytype lockless Steffen Klassert
2016-09-08 5:54 ` [PATCH 13/17] xfrm: policy: only use rcu in xfrm_sk_policy_lookup Steffen Klassert
2016-09-08 5:54 ` [PATCH 14/17] xfrm: policy: don't acquire policy lock in xfrm_spd_getinfo Steffen Klassert
2016-09-08 5:54 ` [PATCH 15/17] xfrm: policy: convert policy_lock to spinlock Steffen Klassert
2016-09-08 5:54 ` [PATCH 16/17] xfrm: Fix xfrm_policy_lock imbalance Steffen Klassert
2016-09-08 5:54 ` [PATCH 17/17] xfrm: state: remove per-netns gc task Steffen Klassert
2016-09-08 20:10 ` pull request (net-next): ipsec-next 2016-09-08 David Miller
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