Re: [PATCH net-next v3] selftests: drv-net: add BIG TCP test cases

diff --git a/tools/testing/selftests/drivers/net/gro_lib.py b/tools/testing/selftests/drivers/net/gro_lib.py
index b7ac0660adc01..abecf60baa537 100644
--- a/tools/testing/selftests/drivers/net/gro_lib.py
+++ b/tools/testing/selftests/drivers/net/gro_lib.py

@@ -91,6 +97,34 @@ def _set_mtu_restore(dev, mtu, host):
         defer(ip, f"link set dev {dev['ifname']} mtu {dev['mtu']}", host=host)
 
 
+def _set_gro_size_restore(cfg, size):
+    """
+    Set the local device's GRO size limits, then confirm they stuck.
+    """
+
+    _set_mtu_restore(cfg.dev, 4096, None)
+    _set_mtu_restore(cfg.remote_dev, 4096, cfg.remote)
+
+    if "gro_max_size" not in cfg.dev or "gro_ipv4_max_size" not in cfg.dev:
+        raise KsftSkipEx("iproute2 does not report the GRO size limits")
+
+    if (cfg.dev["gro_max_size"] == size and
+            cfg.dev["gro_ipv4_max_size"] == size):
+        return
+
+    old = (f"gro_max_size {cfg.dev['gro_max_size']} "
+           f"gro_ipv4_max_size {cfg.dev['gro_ipv4_max_size']}")
+    new = f"gro_max_size {size} gro_ipv4_max_size {size}"
+
+    ip(f"link set dev {cfg.ifname} {new}")
+    defer(ip, f"link set dev {cfg.ifname} {old}")

@@ -239,7 +273,11 @@ def _setup(cfg, mode, test_name):
         flush_path = f"/sys/class/net/{cfg.ifname}/gro_flush_timeout"
         irq_path = f"/sys/class/net/{cfg.ifname}/napi_defer_hard_irqs"
 
-        ctl_file_write(flush_path, "200000")
+        # "big_tcp_*" tests need a longer timeout, use 2x the regular timeout
+        if test_name.startswith("big_tcp_"):
+            ctl_file_write(flush_path, "400000")
+        else:
+            ctl_file_write(flush_path, "200000")
         ctl_file_write(irq_path, "10")

@@ -322,6 +368,10 @@ def _gro_variants():
         for test_name in common_tests:
             yield protocol, test_name
 
+        if protocol in ["ipv4", "ipv6"]:
+            for test_name in big_tcp_tests:
+                yield protocol, test_name
+

         if protocol in ["ipv4", "ipip"]:
             for test_name in ipv4_tests:
                 yield protocol, test_name

@@ -358,7 +408,8 @@ def run_test(cfg, mode, protocol, test_name):
         if rx_proc.ret == 42:
             raise KsftFailEx(f"GRO over-coalesced in {protocol}/{test_name}")
 
-        if test_name.startswith("large_") and os.environ.get("KSFT_MACHINE_SLOW"):
+        if (test_name.startswith(("large_", "big_tcp_")) and
+                os.environ.get("KSFT_MACHINE_SLOW")):
             ksft_pr(f"Ignoring {protocol}/{test_name} failure due to slow environment")
             return

diff --git a/tools/testing/selftests/net/lib/gro.c b/tools/testing/selftests/net/lib/gro.c
index 7a333155de1ab..70b0deb3c11fa 100644
--- a/tools/testing/selftests/net/lib/gro.c
+++ b/tools/testing/selftests/net/lib/gro.c

@@ -166,6 +182,27 @@ static int num_large_pkt(void)
 	return max_payload() / calc_mss();
 }
 
+/* How many maximum sized segments fit under the configured limit. */
+static int big_tcp_large_cnt(void)
+{
+	return (BIG_TCP_GRO_MAX_SIZE - 1 - (total_hdr_len - ETH_HLEN)) /
+	       calc_mss();
+}
+
+/* How many calc_mss() sized segments are needed to satisfy the
+ * following condition:
+ * pkt_count * calc_mss() < IP_MAXPACKET < (pkt_count + 1) * calc_mss()
+ */
+static int big_tcp_fill_cnt(void)
+{
+	return IP_MAXPACKET / calc_mss();
+}

@@ -1161,7 +1253,7 @@ static void recv_error(int fd, int rcv_errno)
 static void check_recv_pkts(int fd, int *correct_payload,
 			    int correct_num_pkts)
 {
-	static char buffer[IP_MAXPACKET + L2_HLEN_MAX + 1];
+	static char buffer[BIG_TCP_RECV_BUF_LEN];

@@ -1541,6 +1633,25 @@ static void gro_sender(void)
 		send_large(txfd, &daddr, remainder + 1);
 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
 
+	/* big tcp sub-tests */
+	} else if (strcmp(testname, "big_tcp_data_same") == 0) {
+		send_big_tcp(txfd, &daddr, calc_mss(), big_tcp_fill_cnt(),
+			     calc_mss());
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

@@ -1768,6 +1879,26 @@ static void gro_receiver(void)
 		printf("last segment sent individually: ");
 		check_recv_pkts(rxfd, correct_payload, 3);
 
+	/* big tcp sub-tests */
+	} else if (strcmp(testname, "big_tcp_data_same") == 0) {
+		correct_payload[0] = big_tcp_fill_len() + calc_mss();
+		printf("data packets of same size past IP_MAXPACKET: ");
+		check_recv_pkts(rxfd, correct_payload, 1);
+	} else if (strcmp(testname, "big_tcp_data_lrg_sml") == 0) {
+		correct_payload[0] = big_tcp_fill_len() + calc_mss() / 2;
+		printf("smaller last packet past IP_MAXPACKET: ");
+		check_recv_pkts(rxfd, correct_payload, 1);
+	} else if (strcmp(testname, "big_tcp_tcp_seq") == 0) {
+		correct_payload[0] = (big_tcp_fill_cnt() + 1) * calc_mss();
+		correct_payload[1] = calc_mss();
+		printf("aliased seq past IP_MAXPACKET doesn't coalesce: ");
+		check_recv_pkts(rxfd, correct_payload, 2);
+	} else if (strcmp(testname, "big_tcp_large_max") == 0) {
+		correct_payload[0] = big_tcp_large_cnt() * calc_mss();
+		correct_payload[1] = calc_mss();
+		printf("shouldn't coalesce past gro_max_size: ");
+		check_recv_pkts(rxfd, correct_payload, 2);
+