mctp: no longer rely on net->dev_index_head[]

mctp_dump_addrinfo() is one of the last users of
net->dev_index_head[] in the control path.

Switch to for_each_netdev_dump() for better scalability.

Use C99 for mctp_device_rtnl_msg_handlers[] to prepare
future RTNL removal from mctp_dump_addrinfo()

(mdev->addrs is not yet RCU protected)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Matt Johnston <matt@codeconstruct.com.au>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://patch.msgid.link/20241206223811.1343076-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mctp/device.c b/net/mctp/device.c
index 26ce34b7e88e174cdb6fa65c0d8e5bf6b5a580d7..8e0724c56723de328592bfe5c6fc8085cd3102fe 100644 (file)
--- a/net/mctp/device.c
+++ b/net/mctp/device.c
@@ -20,8 +20,7 @@
 #include <net/sock.h>
 
 struct mctp_dump_cb {
-       int h;
-       int idx;
+       unsigned long ifindex;
        size_t a_idx;
 };
 
@@ -115,43 +114,29 @@ static int mctp_dump_addrinfo(struct sk_buff *skb, struct netlink_callback *cb)
 {
        struct mctp_dump_cb *mcb = (void *)cb->ctx;
        struct net *net = sock_net(skb->sk);
-       struct hlist_head *head;
        struct net_device *dev;
        struct ifaddrmsg *hdr;
        struct mctp_dev *mdev;
-       int ifindex;
-       int idx = 0, rc;
+       int ifindex, rc;
 
        hdr = nlmsg_data(cb->nlh);
        // filter by ifindex if requested
        ifindex = hdr->ifa_index;
 
        rcu_read_lock();
-       for (; mcb->h < NETDEV_HASHENTRIES; mcb->h++, mcb->idx = 0) {
-               idx = 0;
-               head = &net->dev_index_head[mcb->h];
-               hlist_for_each_entry_rcu(dev, head, index_hlist) {
-                       if (idx >= mcb->idx &&
-                           (ifindex == 0 || ifindex == dev->ifindex)) {
-                               mdev = __mctp_dev_get(dev);
-                               if (mdev) {
-                                       rc = mctp_dump_dev_addrinfo(mdev,
-                                                                   skb, cb);
-                                       mctp_dev_put(mdev);
-                                       // Error indicates full buffer, this
-                                       // callback will get retried.
-                                       if (rc < 0)
-                                               goto out;
-                               }
-                       }
-                       idx++;
-                       // reset for next iteration
-                       mcb->a_idx = 0;
-               }
+       for_each_netdev_dump(net, dev, mcb->ifindex) {
+               if (ifindex && ifindex != dev->ifindex)
+                       continue;
+               mdev = __mctp_dev_get(dev);
+               if (!mdev)
+                       continue;
+               rc = mctp_dump_dev_addrinfo(mdev, skb, cb);
+               mctp_dev_put(mdev);
+               if (rc < 0)
+                       break;
+               mcb->a_idx = 0;
        }
-out:
        rcu_read_unlock();
-       mcb->idx = idx;
 
        return skb->len;
 }
@@ -531,9 +516,12 @@ static struct notifier_block mctp_dev_nb = {
 };
 
 static const struct rtnl_msg_handler mctp_device_rtnl_msg_handlers[] = {
-       {THIS_MODULE, PF_MCTP, RTM_NEWADDR, mctp_rtm_newaddr, NULL, 0},
-       {THIS_MODULE, PF_MCTP, RTM_DELADDR, mctp_rtm_deladdr, NULL, 0},
-       {THIS_MODULE, PF_MCTP, RTM_GETADDR, NULL, mctp_dump_addrinfo, 0},
+       {.owner = THIS_MODULE, .protocol = PF_MCTP, .msgtype = RTM_NEWADDR,
+        .doit = mctp_rtm_newaddr},
+       {.owner = THIS_MODULE, .protocol = PF_MCTP, .msgtype = RTM_DELADDR,
+        .doit = mctp_rtm_deladdr},
+       {.owner = THIS_MODULE, .protocol = PF_MCTP, .msgtype = RTM_GETADDR,
+        .dumpit = mctp_dump_addrinfo},
 };
 
 int __init mctp_device_init(void)