Merge branch 'concurrent_hash_tables'

Thomas Graf says:

====================
Lockless netlink_lookup() with new concurrent hash table

Netlink sockets are maintained in a hash table to allow efficient lookup
via the port ID for unicast messages. However, lookups currently require
a read lock to be taken. This series adds a new generic, resizable,
scalable, concurrent hash table based on the paper referenced in the first
patch. It then makes use of the new data type to implement lockless
netlink_lookup().

Patch 3/3 to convert nft_hash is included for reference but should be
merged via the netfilter tree. Inclusion in this series is to provide
context for the suggested API.

Against net-next since the initial user of the new hash table is in net/

Changes:
v4-v5:
 - use GFP_KERNEL to alloc Netlink buckets as suggested by Nikolay
   Aleksandrov
 - free nft hash element on removal as spotted by Nikolay Aleksandrov
   and Patrick McHardy
v3-v4:
 - fixed wrong shift assignment placement as spotted by Nikolay Aleksandrov
 - reverted default size of nft_hash to 4 as requested by Patrick McHardy,
   default size for other hash tables remains at 64 if no hint is given
 - fixed copyright as requested by Patrick McHardy
v2-v3:
 - fixed typo in nft_hash_destroy() when passing rhashtable handle
v1-v2:
 - fixed traversal off-by-one as spotted by Tobias Klauser
 - removed unlikely() from BUG_ON() as spotted by Josh Triplett
 - new 3rd patch to convert nft_hash to rhashtable
 - make rhashtable_insert() return void
 - nl_sk_hash_lock must be a mutex
 - fixed wrong name of rht_shrink_below_30()
 - exported symbols rht_grow_above_75() and rht_shrink_below_30()
 - allow table freeing with RCU callback
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 3 deletions

diff --git a/net/netlink/diag.c b/net/netlink/diag.c
index 1af29624b92..7301850eb56 100644
--- a/net/netlink/diag.c
+++ b/net/netlink/diag.c
@@ -4,6 +4,7 @@
 #include <linux/netlink.h>
 #include <linux/sock_diag.h>
 #include <linux/netlink_diag.h>
+#include <linux/rhashtable.h>
 
 #include "af_netlink.h"
 
@@ -101,16 +102,20 @@ static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 				int protocol, int s_num)
 {
 	struct netlink_table *tbl = &nl_table[protocol];
-	struct nl_portid_hash *hash = &tbl->hash;
+	struct rhashtable *ht = &tbl->hash;
+	const struct bucket_table *htbl = rht_dereference(ht->tbl, ht);
 	struct net *net = sock_net(skb->sk);
 	struct netlink_diag_req *req;
+	struct netlink_sock *nlsk;
 	struct sock *sk;
 	int ret = 0, num = 0, i;
 
 	req = nlmsg_data(cb->nlh);
 
-	for (i = 0; i <= hash->mask; i++) {
-		sk_for_each(sk, &hash->table[i]) {
+	for (i = 0; i < htbl->size; i++) {
+		rht_for_each_entry(nlsk, htbl->buckets[i], ht, node) {
+			sk = (struct sock *)nlsk;
+
 			if (!net_eq(sock_net(sk), net))
 				continue;
 			if (num < s_num) {