diff options
| author | Florian Westphal <fw@strlen.de> | 2016-08-11 15:17:53 +0200 |
|---|---|---|
| committer | Steffen Klassert <steffen.klassert@secunet.com> | 2016-08-12 08:07:11 +0200 |
| commit | e1e551bc56302b80ff930c966f9985095fb1b70d (patch) | |
| tree | babb24413c09e1ab5ca3a6d690320b05d499204f /net/xfrm | |
| parent | a5eefc1df641f3c99fe54b309e7b79c18cec4a1e (diff) | |
xfrm: policy: prepare policy_bydst hash for rcu lookups
Since commit 56f047305dd4b6b617
("xfrm: add rcu grace period in xfrm_policy_destroy()") xfrm policy
objects are already free'd via rcu.
In order to make more places lockless (i.e. use rcu_read_lock instead of
grabbing read-side of policy rwlock) we only need to:
- use rcu_assign_pointer to store address of new hash table backend memory
- add rcu barrier so that freeing of old memory is delayed (expansion
and free happens from system workqueue, so synchronize_rcu is fine)
- use rcu_dereference to fetch current address of the hash table.
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 | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 93b8ff74001f..4a8d90a88c83 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -385,9 +385,11 @@ static struct hlist_head *policy_hash_bysel(struct net *net, __get_hash_thresh(net, family, dir, &dbits, &sbits); hash = __sel_hash(sel, family, hmask, dbits, sbits); - return (hash == hmask + 1 ? - &net->xfrm.policy_inexact[dir] : - net->xfrm.policy_bydst[dir].table + hash); + if (hash == hmask + 1) + return &net->xfrm.policy_inexact[dir]; + + return rcu_dereference_check(net->xfrm.policy_bydst[dir].table, + lockdep_is_held(&net->xfrm.xfrm_policy_lock)) + hash; } static struct hlist_head *policy_hash_direct(struct net *net, @@ -403,7 +405,8 @@ static struct hlist_head *policy_hash_direct(struct net *net, __get_hash_thresh(net, family, dir, &dbits, &sbits); hash = __addr_hash(daddr, saddr, family, hmask, dbits, sbits); - return net->xfrm.policy_bydst[dir].table + hash; + return rcu_dereference_check(net->xfrm.policy_bydst[dir].table, + lockdep_is_held(&net->xfrm.xfrm_policy_lock)) + hash; } static void xfrm_dst_hash_transfer(struct net *net, @@ -468,8 +471,8 @@ static void xfrm_bydst_resize(struct net *net, int dir) unsigned int hmask = net->xfrm.policy_bydst[dir].hmask; unsigned int nhashmask = xfrm_new_hash_mask(hmask); unsigned int nsize = (nhashmask + 1) * sizeof(struct hlist_head); - struct hlist_head *odst = net->xfrm.policy_bydst[dir].table; struct hlist_head *ndst = xfrm_hash_alloc(nsize); + struct hlist_head *odst; int i; if (!ndst) @@ -477,14 +480,19 @@ static void xfrm_bydst_resize(struct net *net, int dir) write_lock_bh(&net->xfrm.xfrm_policy_lock); + odst = rcu_dereference_protected(net->xfrm.policy_bydst[dir].table, + lockdep_is_held(&net->xfrm.xfrm_policy_lock)); + for (i = hmask; i >= 0; i--) xfrm_dst_hash_transfer(net, odst + i, ndst, nhashmask, dir); - net->xfrm.policy_bydst[dir].table = ndst; + rcu_assign_pointer(net->xfrm.policy_bydst[dir].table, ndst); net->xfrm.policy_bydst[dir].hmask = nhashmask; write_unlock_bh(&net->xfrm.xfrm_policy_lock); + synchronize_rcu(); + xfrm_hash_free(odst, (hmask + 1) * sizeof(struct hlist_head)); } |