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authorKuniyuki Iwashima <kuniyu@amazon.com>2022-06-21 20:19:10 +0300
committerDavid S. Miller <davem@davemloft.net>2022-06-22 14:59:43 +0300
commitb6e811383062f88212082714db849127fa95142c (patch)
tree5999695ff674144ba8e4ec4199c30015203fcecf /net/unix
parentf302d180c6d430ea99643b9b2b3407aedaa36703 (diff)
downloadlinux-b6e811383062f88212082714db849127fa95142c.tar.xz
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@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/unix')
-rw-r--r--net/unix/af_unix.c38
1 files changed, 32 insertions, 6 deletions
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);
}