[PATCH RFC net-next 10/11] selftests: udp gso with corking

[Willem de Bruijn]

From: Willem de Bruijn <will...@google.com>

Corked sockets take a different path to construct a udp datagram than
the lockless fast path. Test this alternate path.

Segmentation offload requires checksum offload, which is not supported
with corked sockets. This test fails after commit d749c9cbffd6
("ipv4: no CHECKSUM_PARTIAL on MSG_MORE corked sockets") and commit
682b1a9d3f96 ("ipv6: no CHECKSUM_PARTIAL on MSG_MORE corked sockets").

Signed-off-by: Willem de Bruijn <will...@google.com>
---
 tools/testing/selftests/net/udpgso.c  | 42 ++++++++++++++++++++-------
 tools/testing/selftests/net/udpgso.sh |  8 +++++
 2 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/net/udpgso.c 
b/tools/testing/selftests/net/udpgso.c
index a47dca025346..6b1998b9f7df 100644
--- a/tools/testing/selftests/net/udpgso.c
+++ b/tools/testing/selftests/net/udpgso.c
@@ -49,6 +49,7 @@ static bool           cfg_do_ipv4;
 static bool            cfg_do_ipv6;
 static bool            cfg_do_connected;
 static bool            cfg_do_connectionless;
+static bool            cfg_do_msgmore;
 static bool            cfg_do_setsockopt;
 static int             cfg_specific_test_id = -1;
 
@@ -369,6 +370,23 @@ static void set_route_mtu(int mtu, bool is_ipv4)
        fprintf(stderr, "route mtu (test): %u\n", mtu);
 }
 
+static bool __send_one(int fd, struct msghdr *msg, int flags)
+{
+       int ret;
+
+       ret = sendmsg(fd, msg, flags);
+       if (ret == -1 && (errno == EMSGSIZE || errno == ENOMEM))
+               return false;
+       if (ret == -1)
+               error(1, errno, "sendmsg");
+       if (ret != msg->msg_iov->iov_len)
+               error(1, 0, "sendto: %d != %lu", ret, msg->msg_iov->iov_len);
+       if (msg->msg_flags)
+               error(1, 0, "sendmsg: return flags 0x%x\n", msg->msg_flags);
+
+       return true;
+}
+
 static bool send_one(int fd, int len, int gso_len,
                     struct sockaddr *addr, socklen_t alen)
 {
@@ -376,7 +394,6 @@ static bool send_one(int fd, int len, int gso_len,
        struct msghdr msg = {0};
        struct iovec iov = {0};
        struct cmsghdr *cm;
-       int ret;
 
        iov.iov_base = buf;
        iov.iov_len = len;
@@ -398,15 +415,17 @@ static bool send_one(int fd, int len, int gso_len,
                *((uint16_t *) CMSG_DATA(cm)) = gso_len;
        }
 
-       ret = sendmsg(fd, &msg, 0);
-       if (ret == -1 && (errno == EMSGSIZE || errno == ENOMEM))
-               return false;
-       if (ret == -1)
-               error(1, errno, "sendmsg");
-       if (ret != len)
-               error(1, 0, "sendto: %d != %u", ret, len);
+       /* If MSG_MORE, send 1 byte followed by remainder */
+       if (cfg_do_msgmore && len > 1) {
+               iov.iov_len = 1;
+               if (!__send_one(fd, &msg, MSG_MORE))
+                       error(1, 0, "send 1B failed");
 
-       return true;
+               iov.iov_base++;
+               iov.iov_len = len - 1;
+       }
+
+       return __send_one(fd, &msg, 0);
 }
 
 static int recv_one(int fd, int flags)
@@ -558,7 +577,7 @@ static void parse_opts(int argc, char **argv)
 {
        int c;
 
-       while ((c = getopt(argc, argv, "46cCst:")) != -1) {
+       while ((c = getopt(argc, argv, "46cCmst:")) != -1) {
                switch (c) {
                case '4':
                        cfg_do_ipv4 = true;
@@ -572,6 +591,9 @@ static void parse_opts(int argc, char **argv)
                case 'C':
                        cfg_do_connectionless = true;
                        break;
+               case 'm':
+                       cfg_do_msgmore = true;
+                       break;
                case 's':
                        cfg_do_setsockopt = true;
                        break;
diff --git a/tools/testing/selftests/net/udpgso.sh 
b/tools/testing/selftests/net/udpgso.sh
index 7cdf0e7c1dde..47acfbbbae38 100755
--- a/tools/testing/selftests/net/udpgso.sh
+++ b/tools/testing/selftests/net/udpgso.sh
@@ -21,3 +21,11 @@ echo "ipv4 connected"
 # blocked on 2nd loopback address
 # echo "ipv6 connected"
 # ./in_netns.sh ./udpgso -6 -c
+
+# ip forces CHECKSUM_NONE with MSG_MORE
+# echo "ipv4 msg_more"
+# ./in_netns.sh ./udpgso -4 -C -m
+
+# ipv6 forces CHECKSUM_NONE with MSG_MORE
+# echo "ipv6 msg_more"
+# ./in_netns.sh ./udpgso -6 -C -m
-- 
2.17.0.484.g0c8726318c-goog