From eaf228263921cd15962654b539d916380a0f076e Mon Sep 17 00:00:00 2001 From: Steffen Klassert Date: Fri, 2 Jul 2021 09:20:22 +0200 Subject: Revert "xfrm: policy: Read seqcount outside of rcu-read side in xfrm_policy_lookup_bytype" This reverts commit d7b0408934c749f546b01f2b33d07421a49b6f3e. This commit tried to fix a locking bug introduced by commit 77cc278f7b20 ("xfrm: policy: Use sequence counters with associated lock"). As it turned out, this patch did not really fix the bug. A proper fix for this bug is applied on top of this revert. Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_policy.c | 21 +++++++-------------- 1 file changed, 7 insertions(+), 14 deletions(-) diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index e9d0df2a2ab1..ce500f847b99 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -2092,15 +2092,12 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type, if (unlikely(!daddr || !saddr)) return NULL; - retry: - sequence = read_seqcount_begin(&xfrm_policy_hash_generation); rcu_read_lock(); - - chain = policy_hash_direct(net, daddr, saddr, family, dir); - if (read_seqcount_retry(&xfrm_policy_hash_generation, sequence)) { - rcu_read_unlock(); - goto retry; - } + retry: + do { + sequence = read_seqcount_begin(&xfrm_policy_hash_generation); + chain = policy_hash_direct(net, daddr, saddr, family, dir); + } while (read_seqcount_retry(&xfrm_policy_hash_generation, sequence)); ret = NULL; hlist_for_each_entry_rcu(pol, chain, bydst) { @@ -2131,15 +2128,11 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type, } skip_inexact: - if (read_seqcount_retry(&xfrm_policy_hash_generation, sequence)) { - rcu_read_unlock(); + if (read_seqcount_retry(&xfrm_policy_hash_generation, sequence)) goto retry; - } - if (ret && !xfrm_pol_hold_rcu(ret)) { - rcu_read_unlock(); + if (ret && !xfrm_pol_hold_rcu(ret)) goto retry; - } fail: rcu_read_unlock(); -- cgit v1.2.3