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nft_hash: Remove rhashtable_remove_pprev()

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The removal function of nft_hash currently stores a reference to the
previous element during lookup which is used to optimize removal later
on. This was possible because a lock is held throughout calling
rhashtable_lookup() and rhashtable_remove().

With the introdution of deferred table resizing in parallel to lookups
and insertions, the nftables lock will no longer synchronize all
table mutations and the stored pprev may become invalid.

Removing this optimization makes removal slightly more expensive on
average but allows taking the resize cost out of the insert and
remove path.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Cc: netfilter-devel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Thomas Graf
2015-01-02 23:00:18 +01:00
committed by David S. Miller
parent b8e1943e9f
commit 897362e446
3 changed files with 10 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files
net/netfilter/nft_hash.c
+3 -8
View File
@@ -83,15 +83,10 @@ static void nft_hash_remove(const struct nft_set *set,
const struct nft_set_elem *elem)
{
struct rhashtable *priv = nft_set_priv(set);
struct rhash_head *he, __rcu **pprev;
pprev = elem->cookie;
he = rht_dereference((*pprev), priv);
rhashtable_remove_pprev(priv, he, pprev);
rhashtable_remove(priv, elem->cookie);
synchronize_rcu();
kfree(he);
kfree(elem->cookie);
}
struct nft_compare_arg {
@@ -105,7 +100,7 @@ static bool nft_hash_compare(void *ptr, void *arg)
struct nft_compare_arg *x = arg;
if (!nft_data_cmp(&he->key, &x->elem->key, x->set->klen)) {
x->elem->cookie = &he->node;
x->elem->cookie = he;
x->elem->flags = 0;
if (x->set->flags & NFT_SET_MAP)
nft_data_copy(&x->elem->data, he->data);