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

From 8d6d303be80c246cf0c92b143432aede255c9238 Mon Sep 17 00:00:00 2001
From: Lei Chen <raychen@qiyi.com>
Date: Fri, 3 Mar 2017 14:49:17 +0800
Subject: [PATCH] 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
not easy to address.
---
 lib/librte_eal/linuxapp/kni/kni_net.c | 67 +++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/lib/librte_eal/linuxapp/kni/kni_net.c b/lib/librte_eal/linuxapp/kni/kni_net.c
index fc82193..952e9b8 100644
--- a/lib/librte_eal/linuxapp/kni/kni_net.c
+++ b/lib/librte_eal/linuxapp/kni/kni_net.c
@@ -35,6 +35,8 @@
 #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>
@@ -527,9 +529,74 @@ kni_net_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 	return 0;
 }
 
+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_KERNEL);
+	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 ? */
+	KNI_DBG("%s: rx-mode/multicast-list changed\n", __func__);
+	rtnl_notify(skb, net, 0, RTNLGRP_NOTIFY, NULL, GFP_KERNEL);
+	return;
 }
 
 static int
-- 
2.7.4