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Message-ID: <20220620185151.65294-4-kuniyu@amazon.com>
Date: Mon, 20 Jun 2022 11:51:48 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
CC: Amit Shah <aams@...zon.com>, Kuniyuki Iwashima <kuniyu@...zon.com>,
Kuniyuki Iwashima <kuni1840@...il.com>,
<netdev@...r.kernel.org>
Subject: [PATCH v2 net-next 3/6] af_unix: Define a per-netns hash table.
This commit adds a per netns hash table for AF_UNIX, which size is fixed
as UNIX_HASH_SIZE for now.
The first implementation defines a per-netns hash table as a single array
of lock and list:
struct unix_hashbucket {
spinlock_t lock;
struct hlist_head head;
};
struct netns_unix {
struct unix_hashbucket *hash;
...
};
But, Eric pointed out memory cost that the structure has holes because of
sizeof(spinlock_t), which is 4 (or more if LOCKDEP is enabled). [0] It
could be expensive on a host with thousands of netns and few AF_UNIX
sockets. For this reason, a per-netns hash table uses two dense arrays.
struct unix_table {
spinlock_t *locks;
struct hlist_head *buckets;
};
struct netns_unix {
struct unix_table table;
...
};
Note the length of the list has a significant impact rather than lock
contention, so having shared locks can be an option. But, per-netns
locks and lists still perform better than the global locks and per-netns
lists. [1]
Also, this patch adds a change so that struct netns_unix disappears from
struct net if CONFIG_UNIX is disabled.
[0]: https://lore.kernel.org/netdev/CANn89iLVxO5aqx16azNU7p7Z-nz5NrnM5QTqOzueVxEnkVTxyg@mail.gmail.com/
[1]: https://lore.kernel.org/netdev/20220617175215.1769-1-kuniyu@amazon.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
include/net/net_namespace.h | 2 ++
include/net/netns/unix.h | 6 ++++++
net/unix/af_unix.c | 38 +++++++++++++++++++++++++++++++------
3 files changed, 40 insertions(+), 6 deletions(-)
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index c4f5601f6e32..20a2992901c2 100644
--- a/include/net/net_namespace.h
+++ b/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)
diff --git a/include/net/netns/unix.h b/include/net/netns/unix.h
index 91a3d7e39198..6f1a33df061d 100644
--- a/include/net/netns/unix.h
+++ b/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;
};
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index c0804ae9c96a..cdd12881a39d 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -3559,7 +3559,7 @@ static const struct net_proto_family unix_family_ops = {
static int __net_init unix_net_init(struct net *net)
{
- int error = -ENOMEM;
+ int i;
net->unx.sysctl_max_dgram_qlen = 10;
if (unix_sysctl_register(net))
@@ -3567,18 +3567,44 @@ static int __net_init unix_net_init(struct net *net)
#ifdef CONFIG_PROC_FS
if (!proc_create_net("unix", 0, net->proc_net, &unix_seq_ops,
- sizeof(struct seq_net_private))) {
- unix_sysctl_unregister(net);
- goto out;
+ sizeof(struct seq_net_private)))
+ goto err_sysctl;
+#endif
+
+ net->unx.table.locks = kvmalloc_array(UNIX_HASH_SIZE,
+ sizeof(spinlock_t), GFP_KERNEL);
+ if (!net->unx.table.locks)
+ goto err_proc;
+
+ net->unx.table.buckets = kvmalloc_array(UNIX_HASH_SIZE,
+ sizeof(struct hlist_head),
+ GFP_KERNEL);
+ if (!net->unx.table.buckets)
+ goto free_locks;
+
+ for (i = 0; i < UNIX_HASH_SIZE; i++) {
+ spin_lock_init(&net->unx.table.locks[i]);
+ INIT_HLIST_HEAD(&net->unx.table.buckets[i]);
}
+
+ return 0;
+
+free_locks:
+ kvfree(net->unx.table.locks);
+err_proc:
+#ifdef CONFIG_PROC_FS
+ remove_proc_entry("unix", net->proc_net);
+err_sysctl:
#endif
- error = 0;
+ unix_sysctl_unregister(net);
out:
- return error;
+ return -ENOMEM;
}
static void __net_exit unix_net_exit(struct net *net)
{
+ kvfree(net->unx.table.buckets);
+ kvfree(net->unx.table.locks);
unix_sysctl_unregister(net);
remove_proc_entry("unix", net->proc_net);
}
--
2.30.2
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