inet: annotate devconf data-races

Add READ_ONCE() in ipv4_devconf_get() and corresponding
WRITE_ONCE() in ipv4_devconf_set()

Add IPV4_DEVCONF_RO() and IPV4_DEVCONF_ALL_RO() macros,
and use them when reading devconf fields.

Signed-off-by: Eric Dumazet <[e-mail]>
Reviewed-by: Jiri Pirko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

include/linux/inetdevice.h

···
 };
 
 #define IPV4_DEVCONF(cnf, attr) ((cnf).data[IPV4_DEVCONF_ ## attr - 1])
+#define IPV4_DEVCONF_RO(cnf, attr) READ_ONCE(IPV4_DEVCONF(cnf, attr))
 #define IPV4_DEVCONF_ALL(net, attr) \
 	IPV4_DEVCONF((*(net)->ipv4.devconf_all), attr)
+#define IPV4_DEVCONF_ALL_RO(net, attr) READ_ONCE(IPV4_DEVCONF_ALL(net, attr))
 
-static inline int ipv4_devconf_get(struct in_device *in_dev, int index)
+static inline int ipv4_devconf_get(const struct in_device *in_dev, int index)
 {
 	index--;
-	return in_dev->cnf.data[index];
+	return READ_ONCE(in_dev->cnf.data[index]);
 }
 
 static inline void ipv4_devconf_set(struct in_device *in_dev, int index,
···
 {
 	index--;
 	set_bit(index, in_dev->cnf.state);
-	in_dev->cnf.data[index] = val;
+	WRITE_ONCE(in_dev->cnf.data[index], val);
 }
 
 static inline void ipv4_devconf_setall(struct in_device *in_dev)
···
 	ipv4_devconf_set((in_dev), IPV4_DEVCONF_ ## attr, (val))
 
 #define IN_DEV_ANDCONF(in_dev, attr) \
-	(IPV4_DEVCONF_ALL(dev_net(in_dev->dev), attr) && \
+	(IPV4_DEVCONF_ALL_RO(dev_net(in_dev->dev), attr) && \
 	 IN_DEV_CONF_GET((in_dev), attr))
 
 #define IN_DEV_NET_ORCONF(in_dev, net, attr) \
-	(IPV4_DEVCONF_ALL(net, attr) || \
+	(IPV4_DEVCONF_ALL_RO(net, attr) || \
 	 IN_DEV_CONF_GET((in_dev), attr))
 
 #define IN_DEV_ORCONF(in_dev, attr) \
 	IN_DEV_NET_ORCONF(in_dev, dev_net(in_dev->dev), attr)
 
 #define IN_DEV_MAXCONF(in_dev, attr) \
-	(max(IPV4_DEVCONF_ALL(dev_net(in_dev->dev), attr), \
+	(max(IPV4_DEVCONF_ALL_RO(dev_net(in_dev->dev), attr), \
 	     IN_DEV_CONF_GET((in_dev), attr)))
 
 #define IN_DEV_FORWARD(in_dev)		IN_DEV_CONF_GET((in_dev), FORWARDING)

net/ipv4/devinet.c

···
 		return -EMSGSIZE;
 
 	for (i = 0; i < IPV4_DEVCONF_MAX; i++)
-		((u32 *) nla_data(nla))[i] = in_dev->cnf.data[i];
+		((u32 *) nla_data(nla))[i] = READ_ONCE(in_dev->cnf.data[i]);
 
 	return 0;
 }
···
 }
 
 static int inet_netconf_fill_devconf(struct sk_buff *skb, int ifindex,
-				     struct ipv4_devconf *devconf, u32 portid,
-				     u32 seq, int event, unsigned int flags,
-				     int type)
+				     const struct ipv4_devconf *devconf,
+				     u32 portid, u32 seq, int event,
+				     unsigned int flags, int type)
 {
 	struct nlmsghdr  *nlh;
 	struct netconfmsg *ncm;
···
 
 	if ((all || type == NETCONFA_FORWARDING) &&
 	    nla_put_s32(skb, NETCONFA_FORWARDING,
-			IPV4_DEVCONF(*devconf, FORWARDING)) < 0)
+			IPV4_DEVCONF_RO(*devconf, FORWARDING)) < 0)
 		goto nla_put_failure;
 	if ((all || type == NETCONFA_RP_FILTER) &&
 	    nla_put_s32(skb, NETCONFA_RP_FILTER,
-			IPV4_DEVCONF(*devconf, RP_FILTER)) < 0)
+			IPV4_DEVCONF_RO(*devconf, RP_FILTER)) < 0)
 		goto nla_put_failure;
 	if ((all || type == NETCONFA_MC_FORWARDING) &&
 	    nla_put_s32(skb, NETCONFA_MC_FORWARDING,
-			IPV4_DEVCONF(*devconf, MC_FORWARDING)) < 0)
+			IPV4_DEVCONF_RO(*devconf, MC_FORWARDING)) < 0)
 		goto nla_put_failure;
 	if ((all || type == NETCONFA_BC_FORWARDING) &&
 	    nla_put_s32(skb, NETCONFA_BC_FORWARDING,
-			IPV4_DEVCONF(*devconf, BC_FORWARDING)) < 0)
+			IPV4_DEVCONF_RO(*devconf, BC_FORWARDING)) < 0)
 		goto nla_put_failure;
 	if ((all || type == NETCONFA_PROXY_NEIGH) &&
 	    nla_put_s32(skb, NETCONFA_PROXY_NEIGH,
-			IPV4_DEVCONF(*devconf, PROXY_ARP)) < 0)
+			IPV4_DEVCONF_RO(*devconf, PROXY_ARP)) < 0)
 		goto nla_put_failure;
 	if ((all || type == NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN) &&
 	    nla_put_s32(skb, NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN,
-			IPV4_DEVCONF(*devconf, IGNORE_ROUTES_WITH_LINKDOWN)) < 0)
+			IPV4_DEVCONF_RO(*devconf,
+					IGNORE_ROUTES_WITH_LINKDOWN)) < 0)
 		goto nla_put_failure;
 
 out:

net/ipv4/igmp.c

···
  */
 
 #define IGMP_V1_SEEN(in_dev) \
-	(IPV4_DEVCONF_ALL(dev_net(in_dev->dev), FORCE_IGMP_VERSION) == 1 || \
+	(IPV4_DEVCONF_ALL_RO(dev_net(in_dev->dev), FORCE_IGMP_VERSION) == 1 || \
 	 IN_DEV_CONF_GET((in_dev), FORCE_IGMP_VERSION) == 1 || \
 	 ((in_dev)->mr_v1_seen && \
 	  time_before(jiffies, (in_dev)->mr_v1_seen)))
 #define IGMP_V2_SEEN(in_dev) \
-	(IPV4_DEVCONF_ALL(dev_net(in_dev->dev), FORCE_IGMP_VERSION) == 2 || \
+	(IPV4_DEVCONF_ALL_RO(dev_net(in_dev->dev), FORCE_IGMP_VERSION) == 2 || \
 	 IN_DEV_CONF_GET((in_dev), FORCE_IGMP_VERSION) == 2 || \
 	 ((in_dev)->mr_v2_seen && \
 	  time_before(jiffies, (in_dev)->mr_v2_seen)))

net/ipv4/proc.c

···
 		seq_printf(seq, " %s", snmp4_ipstats_list[i].name);
 
 	seq_printf(seq, "\nIp: %d %d",
-		   IPV4_DEVCONF_ALL(net, FORWARDING) ? 1 : 2,
+		   IPV4_DEVCONF_ALL_RO(net, FORWARDING) ? 1 : 2,
 		   READ_ONCE(net->ipv4.sysctl_ip_default_ttl));
 
 	BUILD_BUG_ON(offsetof(struct ipstats_mib, mibs) != 0);

net/ipv4/route.c

···
 		if (IN_DEV_BFORWARD(in_dev))
 			goto make_route;
 		/* not do cache if bc_forwarding is enabled */
-		if (IPV4_DEVCONF_ALL(net, BC_FORWARDING))
+		if (IPV4_DEVCONF_ALL_RO(net, BC_FORWARDING))
 			do_cache = false;
 		goto brd_input;
 	}
···
 #ifdef CONFIG_IP_MROUTE
 			if (ipv4_is_multicast(dst) &&
 			    !ipv4_is_local_multicast(dst) &&
-			    IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
+			    IPV4_DEVCONF_ALL_RO(net, MC_FORWARDING)) {
 				int err = ipmr_get_route(net, skb,
 							 fl4->saddr, fl4->daddr,
 							 r, portid);