selftest: net: extend msg_zerocopy test with forwarding

Zerocopy skbs are converted to regular copy skbs when data is queued
to a local socket. This happens in the existing test with a sender and
receiver communicating over a veth device.

Zerocopy skbs are sent without copying if egressing a device. Verify
that this behavior is maintained even in the common container setup
where data is forwarded over a veth to the physical device.

Update msg_zerocopy.sh to

1. Have a dummy network device to simulate a physical device.
2. Have forwarding enabled between veth and dummy.
3. Add a tx-only test that sends out dummy via the forwarding path.
4. Verify the exitcode of the sender, which signals zerocopy success.

As dummy drops all packets, this cannot be a TCP connection. Test
the new case with unconnected UDP only.

Update msg_zerocopy.c to
- Accept an argument whether send with zerocopy is expected.
- Return an exitcode whether behavior matched that expectation.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250630194312.1571410-3-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/net/msg_zerocopy.c b/tools/testing/selftests/net/msg_zerocopy.c
index 7ea5fb28c93db27d250a03a518c491b03ae6b628..1d5d3c4e7e872c27b4ed737db162246747d26314 100644 (file)
--- a/tools/testing/selftests/net/msg_zerocopy.c
+++ b/tools/testing/selftests/net/msg_zerocopy.c
@@ -77,6 +77,7 @@
 static int  cfg_cork;
 static bool cfg_cork_mixed;
 static int  cfg_cpu            = -1;           /* default: pin to last cpu */
+static int  cfg_expect_zerocopy        = -1;
 static int  cfg_family         = PF_UNSPEC;
 static int  cfg_ifindex                = 1;
 static int  cfg_payload_len;
@@ -92,9 +93,9 @@ static socklen_t cfg_alen;
 static struct sockaddr_storage cfg_dst_addr;
 static struct sockaddr_storage cfg_src_addr;
 
+static int exitcode;
 static char payload[IP_MAXPACKET];
 static long packets, bytes, completions, expected_completions;
-static int  zerocopied = -1;
 static uint32_t next_completion;
 static uint32_t sends_since_notify;
 
@@ -444,11 +445,13 @@ static bool do_recv_completion(int fd, int domain)
        next_completion = hi + 1;
 
        zerocopy = !(serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED);
-       if (zerocopied == -1)
-               zerocopied = zerocopy;
-       else if (zerocopied != zerocopy) {
-               fprintf(stderr, "serr: inconsistent\n");
-               zerocopied = zerocopy;
+       if (cfg_expect_zerocopy != -1 &&
+           cfg_expect_zerocopy != zerocopy) {
+               fprintf(stderr, "serr: ee_code: %u != expected %u\n",
+                       zerocopy, cfg_expect_zerocopy);
+               exitcode = 1;
+               /* suppress repeated messages */
+               cfg_expect_zerocopy = zerocopy;
        }
 
        if (cfg_verbose >= 2)
@@ -571,7 +574,7 @@ static void do_tx(int domain, int type, int protocol)
 
        fprintf(stderr, "tx=%lu (%lu MB) txc=%lu zc=%c\n",
                packets, bytes >> 20, completions,
-               zerocopied == 1 ? 'y' : 'n');
+               cfg_zerocopy && cfg_expect_zerocopy == 1 ? 'y' : 'n');
 }
 
 static int do_setup_rx(int domain, int type, int protocol)
@@ -715,7 +718,7 @@ static void parse_opts(int argc, char **argv)
 
        cfg_payload_len = max_payload_len;
 
-       while ((c = getopt(argc, argv, "46c:C:D:i:l:mp:rs:S:t:vz")) != -1) {
+       while ((c = getopt(argc, argv, "46c:C:D:i:l:mp:rs:S:t:vzZ:")) != -1) {
                switch (c) {
                case '4':
                        if (cfg_family != PF_UNSPEC)
@@ -770,6 +773,9 @@ static void parse_opts(int argc, char **argv)
                case 'z':
                        cfg_zerocopy = true;
                        break;
+               case 'Z':
+                       cfg_expect_zerocopy = !!atoi(optarg);
+                       break;
                }
        }
 
@@ -817,5 +823,5 @@ int main(int argc, char **argv)
        else
                error(1, 0, "unknown cfg_test %s", cfg_test);
 
-       return 0;
+       return exitcode;
 }

diff --git a/tools/testing/selftests/net/msg_zerocopy.sh b/tools/testing/selftests/net/msg_zerocopy.sh
index 89c22f5320e0d603ae7ca7ca2b64ebd83bb8979a..28178a38a4e7b50b14480c91dd08adc25542d570 100755 (executable)
--- a/tools/testing/selftests/net/msg_zerocopy.sh
+++ b/tools/testing/selftests/net/msg_zerocopy.sh
@@ -6,6 +6,7 @@
 set -e
 
 readonly DEV="veth0"
+readonly DUMMY_DEV="dummy0"
 readonly DEV_MTU=65535
 readonly BIN="./msg_zerocopy"
 
@@ -14,21 +15,25 @@ readonly NSPREFIX="ns-${RAND}"
 readonly NS1="${NSPREFIX}1"
 readonly NS2="${NSPREFIX}2"
 
-readonly SADDR4='192.168.1.1'
-readonly DADDR4='192.168.1.2'
-readonly SADDR6='fd::1'
-readonly DADDR6='fd::2'
+readonly LPREFIX4='192.168.1'
+readonly RPREFIX4='192.168.2'
+readonly LPREFIX6='fd'
+readonly RPREFIX6='fc'
+
 
 readonly path_sysctl_mem="net.core.optmem_max"
 
 # No arguments: automated test
 if [[ "$#" -eq "0" ]]; then
-       $0 4 tcp -t 1
-       $0 6 tcp -t 1
-       $0 4 udp -t 1
-       $0 6 udp -t 1
-       echo "OK. All tests passed"
-       exit 0
+       ret=0
+
+       $0 4 tcp -t 1 || ret=1
+       $0 6 tcp -t 1 || ret=1
+       $0 4 udp -t 1 || ret=1
+       $0 6 udp -t 1 || ret=1
+
+       [[ "$ret" == "0" ]] && echo "OK. All tests passed"
+       exit $ret
 fi
 
 # Argument parsing
@@ -45,11 +50,18 @@ readonly EXTRA_ARGS="$@"
 
 # Argument parsing: configure addresses
 if [[ "${IP}" == "4" ]]; then
-       readonly SADDR="${SADDR4}"
-       readonly DADDR="${DADDR4}"
+       readonly SADDR="${LPREFIX4}.1"
+       readonly DADDR="${LPREFIX4}.2"
+       readonly DUMMY_ADDR="${RPREFIX4}.1"
+       readonly DADDR_TXONLY="${RPREFIX4}.2"
+       readonly MASK="24"
 elif [[ "${IP}" == "6" ]]; then
-       readonly SADDR="${SADDR6}"
-       readonly DADDR="${DADDR6}"
+       readonly SADDR="${LPREFIX6}::1"
+       readonly DADDR="${LPREFIX6}::2"
+       readonly DUMMY_ADDR="${RPREFIX6}::1"
+       readonly DADDR_TXONLY="${RPREFIX6}::2"
+       readonly MASK="64"
+       readonly NODAD="nodad"
 else
        echo "Invalid IP version ${IP}"
        exit 1
@@ -89,33 +101,61 @@ ip netns exec "${NS2}" sysctl -w -q "${path_sysctl_mem}=1000000"
 ip link add "${DEV}" mtu "${DEV_MTU}" netns "${NS1}" type veth \
   peer name "${DEV}" mtu "${DEV_MTU}" netns "${NS2}"
 
+ip link add "${DUMMY_DEV}" mtu "${DEV_MTU}" netns "${NS2}" type dummy
+
 # Bring the devices up
 ip -netns "${NS1}" link set "${DEV}" up
 ip -netns "${NS2}" link set "${DEV}" up
+ip -netns "${NS2}" link set "${DUMMY_DEV}" up
 
 # Set fixed MAC addresses on the devices
 ip -netns "${NS1}" link set dev "${DEV}" address 02:02:02:02:02:02
 ip -netns "${NS2}" link set dev "${DEV}" address 06:06:06:06:06:06
 
 # Add fixed IP addresses to the devices
-ip -netns "${NS1}" addr add 192.168.1.1/24 dev "${DEV}"
-ip -netns "${NS2}" addr add 192.168.1.2/24 dev "${DEV}"
-ip -netns "${NS1}" addr add       fd::1/64 dev "${DEV}" nodad
-ip -netns "${NS2}" addr add       fd::2/64 dev "${DEV}" nodad
+ip -netns "${NS1}" addr add "${SADDR}/${MASK}" dev "${DEV}" ${NODAD}
+ip -netns "${NS2}" addr add "${DADDR}/${MASK}" dev "${DEV}" ${NODAD}
+ip -netns "${NS2}" addr add "${DUMMY_ADDR}/${MASK}" dev "${DUMMY_DEV}" ${NODAD}
+
+ip -netns "${NS1}" route add default via "${DADDR}" dev "${DEV}"
+ip -netns "${NS2}" route add default via "${DADDR_TXONLY}" dev "${DUMMY_DEV}"
+
+ip netns exec "${NS2}" sysctl -wq net.ipv4.ip_forward=1
+ip netns exec "${NS2}" sysctl -wq net.ipv6.conf.all.forwarding=1
 
 # Optionally disable sg or csum offload to test edge cases
 # ip netns exec "${NS1}" ethtool -K "${DEV}" sg off
 
+ret=0
+
 do_test() {
        local readonly ARGS="$1"
 
-       echo "ipv${IP} ${TXMODE} ${ARGS}"
-       ip netns exec "${NS2}" "${BIN}" "-${IP}" -i "${DEV}" -t 2 -C 2 -S "${SADDR}" -D "${DADDR}" ${ARGS} -r "${RXMODE}" &
+       # tx-rx test
+       # packets queued to a local socket are copied,
+       # sender notification has SO_EE_CODE_ZEROCOPY_COPIED.
+
+       echo -e "\nipv${IP} ${TXMODE} ${ARGS} tx-rx\n"
+       ip netns exec "${NS2}" "${BIN}" "-${IP}" -i "${DEV}" -t 2 -C 2 \
+               -S "${SADDR}" -D "${DADDR}" ${ARGS} -r "${RXMODE}" &
        sleep 0.2
-       ip netns exec "${NS1}" "${BIN}" "-${IP}" -i "${DEV}" -t 1 -C 3 -S "${SADDR}" -D "${DADDR}" ${ARGS} "${TXMODE}"
+       ip netns exec "${NS1}" "${BIN}" "-${IP}" -i "${DEV}" -t 1 -C 3 \
+               -S "${SADDR}" -D "${DADDR}" ${ARGS} "${TXMODE}" -Z 0 || ret=1
        wait
+
+       # next test is unconnected tx to dummy0, cannot exercise with tcp
+       [[ "${TXMODE}" == "tcp" ]] && return
+
+       # tx-only test: send out dummy0
+       # packets leaving the host are not copied,
+       # sender notification does not have SO_EE_CODE_ZEROCOPY_COPIED.
+
+       echo -e "\nipv${IP} ${TXMODE} ${ARGS} tx-only\n"
+       ip netns exec "${NS1}" "${BIN}" "-${IP}" -i "${DEV}" -t 1 -C 3 \
+               -S "${SADDR}" -D "${DADDR_TXONLY}" ${ARGS} "${TXMODE}" -Z 1 || ret=1
 }
 
 do_test "${EXTRA_ARGS}"
 do_test "-z ${EXTRA_ARGS}"
-echo ok
+
+[[ "$ret" == "0" ]] && echo "OK"