[PATCH net-next v2 4/8] selftests: drv-net: gro: prepare for ip6ip6 support

Jakub Kicinski
2026-04-02T21:00:12Z

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.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
tools/testing/selftests/net/lib/gro.c | 73 +++++++++++++++------------
1 file changed, 41 insertions(+), 32 deletions(-)

diff --git a/tools/testing/selftests/net/lib/gro.c b/tools/testing/selftests/net/lib/gro.c
index f05398c18e0c..57080ecc3df8 100644
--- 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: ");
--
2.53.0