Merge branch 'af_unix-per-netns-socket-hash'

Kuniyuki Iwashima says:

====================
af_unix: Introduce per-netns socket hash table.

This series replaces unix_socket_table with a per-netns hash table and
reduces lock contention and time on iterating over the list.

Note the 3rd-6th patches can be a single patch, but for ease of review,
they are split into small changes without breakage.

Changes:
  v3:
    6th:
      * Remove unix_table_locks from comments.
      * Remove missed spin_unlock(&unix_table_locks) in
        unix_lookup_by_ino() (kernel test robot)

  v2: https://lore.kernel.org/netdev/20220620185151.65294-1-kuniyu@amazon.com/
    3rd:
      * Update changelog
      * Remove holes from per-netns hash table structure
      * Use kvmalloc_array() instead of kmalloc() (Eric Dumazet)
      * Remove unnecessary parts in af_unix_init() (Eric Dumazet)
      * Move `err_sysctl` label into ifdef block (kernel test robot)
      * Remove struct netns_unix from struct net if CONFIG_UNIX is disabled
    4th:
      * Use spin_lock_nested() (kernel test robot)

  v1: https://lore.kernel.org/netdev/20220616234714.4291-1-kuniyu@amazon.com/
====================

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

include/net/af_unix.h

@@ -16,12 +16,11 @@ void wait_for_unix_gc(void);
 struct sock *unix_get_socket(struct file *filp);
 struct sock *unix_peer_get(struct sock *sk);
 
-#define UNIX_HASH_SIZE	256
+#define UNIX_HASH_MOD	(256 - 1)
+#define UNIX_HASH_SIZE	(256 * 2)
 #define UNIX_HASH_BITS	8
 
 extern unsigned int unix_tot_inflight;
-extern spinlock_t unix_table_locks[2 * UNIX_HASH_SIZE];
-extern struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];
 
 struct unix_address {
 	refcount_t	refcnt;

include/net/net_namespace.h

@@ -120,7 +120,9 @@ struct net {
 	struct netns_core	core;
 	struct netns_mib	mib;
 	struct netns_packet	packet;
+#if IS_ENABLED(CONFIG_UNIX)
 	struct netns_unix	unx;
+#endif
 	struct netns_nexthop	nexthop;
 	struct netns_ipv4	ipv4;
 #if IS_ENABLED(CONFIG_IPV6)

include/net/netns/unix.h

@@ -5,8 +5,14 @@
 #ifndef __NETNS_UNIX_H__
 #define __NETNS_UNIX_H__
 
+struct unix_table {
+	spinlock_t		*locks;
+	struct hlist_head	*buckets;
+};
+
 struct ctl_table_header;
 struct netns_unix {
+	struct unix_table	table;
 	int			sysctl_max_dgram_qlen;
 	struct ctl_table_header	*ctl;
 };