selftests: drv-net: gro: prepare for ip6ip6 support

Try to use already calculated offsets and not depend on the ipip
flag as much. This patch should not change any functionality,
it's just a cleanup to make ip6ip6 support easier.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260402210000.1512696-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/net/lib/gro.c b/tools/testing/selftests/net/lib/gro.c
index f05398c18e0c8227f3608f97c524f35261ed20ff..57080ecc3df8857785bea0561ed69074e868e959 100644 (file)
--- a/tools/testing/selftests/net/lib/gro.c
+++ b/tools/testing/selftests/net/lib/gro.c
@@ -139,6 +139,14 @@ static bool order_check;
 
 #define TXTIME_DELAY_MS 5
 
+/* Max TCP payload that GRO will coalesce. The outer header overhead
+ * varies by encapsulation, reducing the effective max payload.
+ */
+static int max_payload(void)
+{
+       return IP_MAXPACKET - (total_hdr_len - ETH_HLEN);
+}
+
 static void vlog(const char *fmt, ...)
 {
        va_list args;
@@ -156,15 +164,13 @@ static void setup_sock_filter(int fd)
        const int ethproto_off = offsetof(struct ethhdr, h_proto);
        int optlen = 0;
        int ipproto_off, opt_ipproto_off;
-       int next_off;
 
-       if (ipip)
-               next_off = sizeof(struct iphdr) + offsetof(struct iphdr, protocol);
-       else if (proto == PF_INET)
-               next_off = offsetof(struct iphdr, protocol);
+       if (proto == PF_INET)
+               ipproto_off = tcp_offset - sizeof(struct iphdr) +
+                             offsetof(struct iphdr, protocol);
        else
-               next_off = offsetof(struct ipv6hdr, nexthdr);
-       ipproto_off = ETH_HLEN + next_off;
+               ipproto_off = tcp_offset - sizeof(struct ipv6hdr) +
+                             offsetof(struct ipv6hdr, nexthdr);
 
        /* Overridden later if exthdrs are used: */
        opt_ipproto_off = ipproto_off;
@@ -381,19 +387,23 @@ static void write_packet(int fd, char *buf, int len, struct sockaddr_ll *daddr)
 static void create_packet(void *buf, int seq_offset, int ack_offset,
                          int payload_len, int fin)
 {
+       int ip_hdr_len = (proto == PF_INET) ?
+                        sizeof(struct iphdr) : sizeof(struct ipv6hdr);
+       int inner_ip_off = tcp_offset - ip_hdr_len;
+
        memset(buf, 0, total_hdr_len);
        memset(buf + total_hdr_len, 'a', payload_len);
 
        fill_transportlayer(buf + tcp_offset, seq_offset, ack_offset,
                            payload_len, fin);
 
-       if (ipip) {
-               fill_networklayer(buf + ETH_HLEN, payload_len + sizeof(struct iphdr),
-                                 IPPROTO_IPIP);
-               fill_networklayer(buf + ETH_HLEN + sizeof(struct iphdr),
-                                 payload_len, IPPROTO_TCP);
-       } else {
-               fill_networklayer(buf + ETH_HLEN, payload_len, IPPROTO_TCP);
+       fill_networklayer(buf + inner_ip_off, payload_len, IPPROTO_TCP);
+       if (inner_ip_off > ETH_HLEN) {
+               int encap_proto = (proto == PF_INET) ?
+                                 IPPROTO_IPIP : IPPROTO_IPV6;
+
+               fill_networklayer(buf + ETH_HLEN,
+                                 payload_len + ip_hdr_len, encap_proto);
        }
 
        fill_datalinklayer(buf);
@@ -547,8 +557,7 @@ static void send_ack(int fd, struct sockaddr_ll *daddr)
 static void recompute_packet(char *buf, char *no_ext, int extlen)
 {
        struct tcphdr *tcphdr = (struct tcphdr *)(buf + tcp_offset);
-       struct ipv6hdr *ip6h = (struct ipv6hdr *)(buf + ETH_HLEN);
-       struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
+       int off;
 
        memmove(buf, no_ext, total_hdr_len);
        memmove(buf + total_hdr_len + extlen,
@@ -558,18 +567,22 @@ static void recompute_packet(char *buf, char *no_ext, int extlen)
        tcphdr->check = 0;
        tcphdr->check = tcp_checksum(tcphdr, PAYLOAD_LEN + extlen);
        if (proto == PF_INET) {
-               iph->tot_len = htons(ntohs(iph->tot_len) + extlen);
-               iph->check = 0;
-               iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
+               for (off = ETH_HLEN; off < tcp_offset;
+                    off += sizeof(struct iphdr)) {
+                       struct iphdr *iph = (struct iphdr *)(buf + off);
 
-               if (ipip) {
-                       iph += 1;
                        iph->tot_len = htons(ntohs(iph->tot_len) + extlen);
                        iph->check = 0;
                        iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
                }
        } else {
-               ip6h->payload_len = htons(ntohs(ip6h->payload_len) + extlen);
+               for (off = ETH_HLEN; off < tcp_offset;
+                    off += sizeof(struct ipv6hdr)) {
+                       struct ipv6hdr *ip6h = (struct ipv6hdr *)(buf + off);
+
+                       ip6h->payload_len =
+                               htons(ntohs(ip6h->payload_len) + extlen);
+               }
        }
 }
 
@@ -1425,14 +1438,12 @@ static void gro_sender(void)
 
        /* large sub-tests */
        } else if (strcmp(testname, "large_max") == 0) {
-               int offset = (proto == PF_INET && !ipip) ? 20 : 0;
-               int remainder = (MAX_PAYLOAD + offset) % MSS;
+               int remainder = max_payload() % MSS;
 
                send_large(txfd, &daddr, remainder);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "large_rem") == 0) {
-               int offset = (proto == PF_INET && !ipip) ? 20 : 0;
-               int remainder = (MAX_PAYLOAD + offset) % MSS;
+               int remainder = max_payload() % MSS;
 
                send_large(txfd, &daddr, remainder + 1);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
@@ -1636,19 +1647,17 @@ static void gro_receiver(void)
 
        /* large sub-tests */
        } else if (strcmp(testname, "large_max") == 0) {
-               int offset = (proto == PF_INET && !ipip) ? 20 : 0;
-               int remainder = (MAX_PAYLOAD + offset) % MSS;
+               int remainder = max_payload() % MSS;
 
-               correct_payload[0] = (MAX_PAYLOAD + offset);
+               correct_payload[0] = max_payload();
                correct_payload[1] = remainder;
                printf("Shouldn't coalesce if exceed IP max pkt size: ");
                check_recv_pkts(rxfd, correct_payload, 2);
        } else if (strcmp(testname, "large_rem") == 0) {
-               int offset = (proto == PF_INET && !ipip) ? 20 : 0;
-               int remainder = (MAX_PAYLOAD + offset) % MSS;
+               int remainder = max_payload() % MSS;
 
                /* last segment sent individually, doesn't start new segment */
-               correct_payload[0] = (MAX_PAYLOAD + offset) - remainder;
+               correct_payload[0] = max_payload() - remainder;
                correct_payload[1] = remainder + 1;
                correct_payload[2] = remainder + 1;
                printf("last segment sent individually: ");