[PATCH bpf-next 1/3] net: xsk: track AF_XDP sockets on a per-netns list

[bjorn . topel]

From: Björn Töpel <bjorn.to...@intel.com>

Track each AF_XDP socket in a per-netns list. This will be used later
by the sock_diag interface for querying sockets from userspace.

Signed-off-by: Björn Töpel <bjorn.to...@intel.com>
---
 include/net/net_namespace.h |  4 ++++
 include/net/netns/xdp.h     | 13 +++++++++++++
 net/xdp/xsk.c               | 30 ++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+)
 create mode 100644 include/net/netns/xdp.h

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 99d4148e0f90..a68ced28d8f4 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -31,6 +31,7 @@
 #include <net/netns/xfrm.h>
 #include <net/netns/mpls.h>
 #include <net/netns/can.h>
+#include <net/netns/xdp.h>
 #include <linux/ns_common.h>
 #include <linux/idr.h>
 #include <linux/skbuff.h>
@@ -160,6 +161,9 @@ struct net {
 #endif
 #if IS_ENABLED(CONFIG_CAN)
        struct netns_can        can;
+#endif
+#ifdef CONFIG_XDP_SOCKETS
+       struct netns_xdp        xdp;
 #endif
        struct sock             *diag_nlsk;
        atomic_t                fnhe_genid;
diff --git a/include/net/netns/xdp.h b/include/net/netns/xdp.h
new file mode 100644
index 000000000000..e5734261ba0a
--- /dev/null
+++ b/include/net/netns/xdp.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NETNS_XDP_H__
+#define __NETNS_XDP_H__
+
+#include <linux/rculist.h>
+#include <linux/mutex.h>
+
+struct netns_xdp {
+       struct mutex            lock;
+       struct hlist_head       list;
+};
+
+#endif /* __NETNS_XDP_H__ */
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index a03268454a27..80ca48cefc42 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -350,6 +350,10 @@ static int xsk_release(struct socket *sock)
 
        net = sock_net(sk);
 
+       mutex_lock(&net->xdp.lock);
+       sk_del_node_init_rcu(sk);
+       mutex_unlock(&net->xdp.lock);
+
        local_bh_disable();
        sock_prot_inuse_add(net, sk->sk_prot, -1);
        local_bh_enable();
@@ -746,6 +750,10 @@ static int xsk_create(struct net *net, struct socket 
*sock, int protocol,
        mutex_init(&xs->mutex);
        spin_lock_init(&xs->tx_completion_lock);
 
+       mutex_lock(&net->xdp.lock);
+       sk_add_node_rcu(sk, &net->xdp.list);
+       mutex_unlock(&net->xdp.lock);
+
        local_bh_disable();
        sock_prot_inuse_add(net, &xsk_proto, 1);
        local_bh_enable();
@@ -759,6 +767,23 @@ static const struct net_proto_family xsk_family_ops = {
        .owner  = THIS_MODULE,
 };
 
+static int __net_init xsk_net_init(struct net *net)
+{
+       mutex_init(&net->xdp.lock);
+       INIT_HLIST_HEAD(&net->xdp.list);
+       return 0;
+}
+
+static void __net_exit xsk_net_exit(struct net *net)
+{
+       WARN_ON_ONCE(!hlist_empty(&net->xdp.list));
+}
+
+static struct pernet_operations xsk_net_ops = {
+       .init = xsk_net_init,
+       .exit = xsk_net_exit,
+};
+
 static int __init xsk_init(void)
 {
        int err;
@@ -771,8 +796,13 @@ static int __init xsk_init(void)
        if (err)
                goto out_proto;
 
+       err = register_pernet_subsys(&xsk_net_ops);
+       if (err)
+               goto out_sk;
        return 0;
 
+out_sk:
+       sock_unregister(PF_XDP);
 out_proto:
        proto_unregister(&xsk_proto);
 out:
-- 
2.19.1