0001-kni-use-netlink-event-for-multicast-driver-part.patch

From 659c6e84e3ae0c5e5b93894aa15dd4983b3ac6c3 Mon Sep 17 00:00:00 2001
From: ywc689 <ywc689@163.com>
Date: Fri, 28 Jun 2019 16:52:24 +0800
Subject: [PATCH 1/3] kni: use netlink event for multicast (driver part)

kni driver send netlink event every time hw-multicast list updated by
kernel, the user kni app should capture the event and update multicast
to kni device.

original way is using rte_kni_request to pass hw-multicast to user kni
module. that method works but finally memory corruption found, which is
to kni device.
---
 kernel/linux/kni/kni_net.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/kernel/linux/kni/kni_net.c b/kernel/linux/kni/kni_net.c
index 7371b6d..edc1416 100644
--- a/kernel/linux/kni/kni_net.c
+++ b/kernel/linux/kni/kni_net.c
@@ -16,6 +16,8 @@
 #include <linux/skbuff.h>
 #include <linux/kthread.h>
 #include <linux/delay.h>
+#include <linux/inetdevice.h>
+#include <net/netlink.h>
 
 #include <exec-env/rte_kni_common.h>
 #include <kni_fifo.h>
@@ -103,6 +105,7 @@
 	ret_val = wait_event_interruptible_timeout(kni->wq,
 			kni_fifo_count(kni->resp_q), 3 * HZ);
 	if (signal_pending(current) || ret_val <= 0) {
+		pr_err("%s: wait_event_interruptible timeout\n", __func__);
 		ret = -ETIME;
 		goto fail;
 	}
@@ -605,9 +608,75 @@ void kni_net_release_fifo_phy(struct kni_dev *kni)
 	return -EOPNOTSUPP;
 }
 
+static size_t
+kni_nlmsg_size(void)
+{
+    return NLMSG_ALIGN(sizeof(struct ifaddrmsg))
+           + nla_total_size(4) /* IFA_ADDRESS */
+           + nla_total_size(4) /* IFA_LOCAL */
+           + nla_total_size(4) /* IFA_BROADCAST */
+           + nla_total_size(IFNAMSIZ) /* IFA_LABEL */
+           + nla_total_size(4) /* IFA_FLAGS */
+           + nla_total_size(sizeof(struct ifa_cacheinfo)); /* IFA_CACHEINFO */
+}
+
 static void
 kni_net_set_rx_mode(struct net_device *dev)
 {
+    /*
+     * send event to notify user (DPDK KNI app) that multicast list changed,
+     * so that it can monitor multicast join/leave and set HW mc-addrs to
+     * kni dev accordinglly.
+     *
+     * this event is just an notification, we do not save any mc-addr here
+     * (so attribute space for us). user kni app should get maddrs after
+     * receive this notification.
+     *
+     * I was expecting kernel send some rtnl event for multicast join/leave,
+     * but it doesn't. By checking the call-chain of SIOCADDMULTI (ip maddr,
+     * manages only hardware multicast) and IP_ADD_MEMBERSHIP (ip_mc_join_group,
+     * used to for IPv4 multicast), no rtnl event sent.
+     *
+     * so as workaround, modify kni driver here to send RTM_NEWADDR.
+     * it may not suitalbe to use this event for mcast, but that should works.
+     * hope that won't affect other listener to this event.
+     *
+     * previous solution was using rte_kni_request to pass hw-maddr list to user.
+     * it "works" for times but finally memory corruption found, which is
+     * not easy to address (lock was added and reviewed). That's why we use
+     * netlink event instead.
+     */
+    struct sk_buff *skb;
+    struct net *net = dev_net(dev);
+    struct nlmsghdr *nlh;
+    struct ifaddrmsg *ifm;
+
+    skb = nlmsg_new(kni_nlmsg_size(), GFP_ATOMIC);
+    if (!skb)
+        return;
+
+    /* no other event for us ? */
+    nlh = nlmsg_put(skb, 0, 0, RTM_NEWADDR, sizeof(*ifm), 0);
+    if (!nlh) {
+        kfree_skb(skb);
+        return;
+    }
+
+    /* just send an notification so no other info */
+    ifm = nlmsg_data(nlh);
+    memset(ifm, 0, sizeof(*ifm));
+    ifm->ifa_family = AF_UNSPEC;
+    ifm->ifa_prefixlen = 0;
+    ifm->ifa_flags = 0;
+    ifm->ifa_scope = RT_SCOPE_NOWHERE;
+    ifm->ifa_index = 0;
+
+    nlmsg_end(skb, nlh);
+
+    /* other group ? */
+    pr_debug("%s: rx-mode/multicast-list changed\n", __func__);
+    rtnl_notify(skb, net, 0, RTNLGRP_NOTIFY, NULL, GFP_ATOMIC);
+    return;
 }
 
 static int
@@ -727,6 +796,7 @@ void kni_net_release_fifo_phy(struct kni_dev *kni)
 	kni = netdev_priv(netdev);
 	ret = kni_net_process_request(kni, &req);
 
+	pr_info("%s request returns %d!\n", __func__, ret);
 	return (ret == 0 ? req.result : ret);
 }
 
-- 
1.8.3.1