[NET]: Treat the sign of the result of skb_headroom() consistently

In some places, the result of skb_headroom() is compared to an unsigned
integer, and in others, the result is compared to a signed integer.  Make
the comparisons consistent and correct.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index c5b77bb..02b02a8 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -674,7 +674,7 @@
 	struct rtable *rt;     			/* Route to the other host */
 	struct net_device *tdev;			/* Device to other host */
 	struct iphdr  *iph;			/* Our new IP header */
-	int    max_headroom;			/* The extra header space needed */
+	unsigned int max_headroom;		/* The extra header space needed */
 	int    gre_hlen;
 	__be32 dst;
 	int    mtu;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index f508835..e5f7dc2 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -161,7 +161,7 @@
 	struct dst_entry *dst = skb->dst;
 	struct rtable *rt = (struct rtable *)dst;
 	struct net_device *dev = dst->dev;
-	int hh_len = LL_RESERVED_SPACE(dev);
+	unsigned int hh_len = LL_RESERVED_SPACE(dev);
 
 	if (rt->rt_type == RTN_MULTICAST)
 		IP_INC_STATS(IPSTATS_MIB_OUTMCASTPKTS);
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 5cd5bbe..8c2b2b0 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -515,7 +515,7 @@
 	struct net_device *tdev;			/* Device to other host */
 	struct iphdr  *old_iph = ip_hdr(skb);
 	struct iphdr  *iph;			/* Our new IP header */
-	int    max_headroom;			/* The extra header space needed */
+	unsigned int max_headroom;		/* The extra header space needed */
 	__be32 dst = tiph->daddr;
 	int    mtu;
 
diff --git a/net/ipv4/ipvs/ip_vs_xmit.c b/net/ipv4/ipvs/ip_vs_xmit.c
index d0a92de..7c074e3 100644
--- a/net/ipv4/ipvs/ip_vs_xmit.c
+++ b/net/ipv4/ipvs/ip_vs_xmit.c
@@ -325,7 +325,7 @@
 	__be16 df = old_iph->frag_off;
 	sk_buff_data_t old_transport_header = skb->transport_header;
 	struct iphdr  *iph;			/* Our new IP header */
-	int    max_headroom;			/* The extra header space needed */
+	unsigned int max_headroom;		/* The extra header space needed */
 	int    mtu;
 
 	EnterFunction(10);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9288220..3dbbb44 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3909,7 +3909,7 @@
 
 	while (before(start, end)) {
 		struct sk_buff *nskb;
-		int header = skb_headroom(skb);
+		unsigned int header = skb_headroom(skb);
 		int copy = SKB_MAX_ORDER(header, 0);
 
 		/* Too big header? This can happen with IPv6. */