diff options
| author | Florian Westphal <fw@strlen.de> | 2016-08-11 15:17:54 +0200 |
|---|---|---|
| committer | Steffen Klassert <steffen.klassert@secunet.com> | 2016-08-12 08:07:11 +0200 |
| commit | 30846090a746edfdb230deadd638cfa96f7b8c91 (patch) | |
| tree | 3f6aeebcccfc90ad302ea2ce6c567f55d1e52131 /net/xfrm | |
| parent | e1e551bc56302b80ff930c966f9985095fb1b70d (diff) | |
xfrm: policy: add sequence count to sync with hash resize
Once xfrm_policy_lookup_bytype doesn't grab xfrm_policy_lock anymore its
possible for a hash resize to occur in parallel.
Use sequence counter to block lookup in case a resize is in
progress and to also re-lookup in case hash table was altered
in the mean time (might cause use to not find the best-match).
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.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 4a8d90a88c83..576d90321068 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -49,6 +49,7 @@ static struct xfrm_policy_afinfo __rcu *xfrm_policy_afinfo[NPROTO] __read_mostly; static struct kmem_cache *xfrm_dst_cache __read_mostly; +static __read_mostly seqcount_t xfrm_policy_hash_generation; static void xfrm_init_pmtu(struct dst_entry *dst); static int stale_bundle(struct dst_entry *dst); @@ -479,6 +480,10 @@ static void xfrm_bydst_resize(struct net *net, int dir) return; write_lock_bh(&net->xfrm.xfrm_policy_lock); + write_seqcount_begin(&xfrm_policy_hash_generation); + + odst = rcu_dereference_protected(net->xfrm.policy_bydst[dir].table, + lockdep_is_held(&net->xfrm.xfrm_policy_lock)); odst = rcu_dereference_protected(net->xfrm.policy_bydst[dir].table, lockdep_is_held(&net->xfrm.xfrm_policy_lock)); @@ -489,6 +494,7 @@ static void xfrm_bydst_resize(struct net *net, int dir) rcu_assign_pointer(net->xfrm.policy_bydst[dir].table, ndst); net->xfrm.policy_bydst[dir].hmask = nhashmask; + write_seqcount_end(&xfrm_policy_hash_generation); write_unlock_bh(&net->xfrm.xfrm_policy_lock); synchronize_rcu(); @@ -1104,7 +1110,8 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type, struct xfrm_policy *pol, *ret; const xfrm_address_t *daddr, *saddr; struct hlist_head *chain; - u32 priority = ~0U; + unsigned int sequence; + u32 priority; daddr = xfrm_flowi_daddr(fl, family); saddr = xfrm_flowi_saddr(fl, family); @@ -1112,7 +1119,13 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type, return NULL; read_lock_bh(&net->xfrm.xfrm_policy_lock); - chain = policy_hash_direct(net, daddr, saddr, family, dir); + 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)); + + priority = ~0U; ret = NULL; hlist_for_each_entry_rcu(pol, chain, bydst) { err = xfrm_policy_match(pol, fl, type, family, dir); @@ -1148,6 +1161,9 @@ 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); fail: read_unlock_bh(&net->xfrm.xfrm_policy_lock); @@ -3090,6 +3106,7 @@ static struct pernet_operations __net_initdata xfrm_net_ops = { void __init xfrm_init(void) { register_pernet_subsys(&xfrm_net_ops); + seqcount_init(&xfrm_policy_hash_generation); xfrm_input_init(); } |