net: Add FLOWI_FLAG_CAN_SLEEP.

And set is in contexts where the route resolution can sleep.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/flow.h

@@ -50,6 +50,7 @@ struct flowi {
 	__u8	flags;
 #define FLOWI_FLAG_ANYSRC		0x01
 #define FLOWI_FLAG_PRECOW_METRICS	0x02
+#define FLOWI_FLAG_CAN_SLEEP		0x04
 	union {
 		struct {
 			__be16	sport;

include/net/route.h

@@ -185,6 +185,8 @@ static inline int ip_route_connect(struct rtable **rp, __be32 dst,
 		fl.flags |= FLOWI_FLAG_ANYSRC;
 	if (protocol == IPPROTO_TCP)
 		fl.flags |= FLOWI_FLAG_PRECOW_METRICS;
+	if (can_sleep)
+		fl.flags |= FLOWI_FLAG_CAN_SLEEP;
 
 	if (!dst || !src) {
 		err = __ip_route_output_key(net, rp, &fl);

net/ipv4/raw.c

@@ -555,6 +555,7 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 				    .fl4_tos = tos,
 				    .proto = inet->hdrincl ? IPPROTO_RAW :
 							     sk->sk_protocol,
+				    .flags = FLOWI_FLAG_CAN_SLEEP,
 		};
 		if (!inet->hdrincl) {
 			err = raw_probe_proto_opt(&fl, msg);

net/ipv4/udp.c

@@ -914,9 +914,11 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 				    .fl4_src = saddr,
 				    .fl4_tos = tos,
 				    .proto = sk->sk_protocol,
-				    .flags = inet_sk_flowi_flags(sk),
+				    .flags = (inet_sk_flowi_flags(sk) |
+					      FLOWI_FLAG_CAN_SLEEP),
 				    .fl_ip_sport = inet->inet_sport,
-				    .fl_ip_dport = dport };
+				    .fl_ip_dport = dport
+		};
 		struct net *net = sock_net(sk);
 
 		security_sk_classify_flow(sk, &fl);

net/ipv6/ip6_output.c

@@ -1026,6 +1026,7 @@ struct dst_entry *ip6_dst_lookup_flow(struct sock *sk, struct flowi *fl,
 	if (final_dst)
 		ipv6_addr_copy(&fl->fl6_dst, final_dst);
 	if (want_blackhole) {
+		fl->flags |= FLOWI_FLAG_CAN_SLEEP;
 		err = __xfrm_lookup(sock_net(sk), &dst, fl, sk, XFRM_LOOKUP_WAIT);
 		if (err == -EREMOTE)
 			err = ip6_dst_blackhole(sk, &dst, fl);
@@ -1070,6 +1071,7 @@ struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi *fl,
 	if (final_dst)
 		ipv6_addr_copy(&fl->fl6_dst, final_dst);
 	if (want_blackhole) {
+		fl->flags |= FLOWI_FLAG_CAN_SLEEP;
 		err = __xfrm_lookup(sock_net(sk), &dst, fl, sk, XFRM_LOOKUP_WAIT);
 		if (err == -EREMOTE)
 			err = ip6_dst_blackhole(sk, &dst, fl);