Extend psock_snd to test drops by setting a tiny receive buffer and
sending a large burst of packets.

Signed-off-by: Joe Damato <[email protected]>
---
 tools/testing/selftests/net/psock_snd.c  | 52 ++++++++++++++++++++----
 tools/testing/selftests/net/psock_snd.sh |  5 +++
 2 files changed, 48 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/net/psock_snd.c 
b/tools/testing/selftests/net/psock_snd.c
index 5be481a3d2bd..7bbce274b9f0 100644
--- a/tools/testing/selftests/net/psock_snd.c
+++ b/tools/testing/selftests/net/psock_snd.c
@@ -39,6 +39,7 @@ static bool   cfg_use_gso;
 static bool    cfg_use_qdisc_bypass;
 static bool    cfg_use_vlan;
 static bool    cfg_use_vnet;
+static bool    cfg_drop;
 
 static char    *cfg_ifname = "lo";
 static int     cfg_mtu = 1500;
@@ -49,6 +50,8 @@ static uint16_t       cfg_port = 8000;
 /* test sending up to max mtu + 1 */
 #define TEST_SZ        (sizeof(struct virtio_net_hdr) + ETH_HLEN + ETH_MAX_MTU 
+ 1)
 
+#define BURST_CNT (1000)
+
 static char tbuf[TEST_SZ], rbuf[TEST_SZ];
 
 static unsigned long add_csum_hword(const uint16_t *start, int num_u16)
@@ -212,13 +215,14 @@ static void do_send(int fd, char *buf, int len)
        if (ret != len)
                error(1, 0, "write: %u %u", ret, len);
 
-       fprintf(stderr, "tx: %u\n", ret);
+       if (!cfg_drop)
+               fprintf(stderr, "tx: %u\n", ret);
 }
 
-static int do_tx(void)
+static int do_tx(bool burst)
 {
        const int one = 1;
-       int fd, len;
+       int i, fd, len;
 
        fd = socket(PF_PACKET, cfg_use_dgram ? SOCK_DGRAM : SOCK_RAW, 0);
        if (fd == -1)
@@ -242,6 +246,10 @@ static int do_tx(void)
 
        do_send(fd, tbuf, len);
 
+       if (burst)
+               for (i = 0; i < BURST_CNT; i++)
+                       do_send(fd, tbuf, len);
+
        if (close(fd))
                error(1, errno, "close t");
 
@@ -290,6 +298,7 @@ static void do_rx(int fd, int expected_len, char *expected)
 static int setup_sniffer(void)
 {
        struct timeval tv = { .tv_usec = 100 * 1000 };
+       const int one = 1;
        int fd;
 
        fd = socket(PF_PACKET, SOCK_RAW, 0);
@@ -299,6 +308,10 @@ static int setup_sniffer(void)
        if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)))
                error(1, errno, "setsockopt rcv timeout");
 
+       if (cfg_drop)
+               if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &one, sizeof(one)))
+                       error(1, errno, "setsockopt SO_RCVBUF");
+
        pair_udp_setfilter(fd);
        do_bind(fd);
 
@@ -309,7 +322,7 @@ static void parse_opts(int argc, char **argv)
 {
        int c;
 
-       while ((c = getopt(argc, argv, "bcCdgl:qt:vV")) != -1) {
+       while ((c = getopt(argc, argv, "bcCdDgl:qt:vV")) != -1) {
                switch (c) {
                case 'b':
                        cfg_use_bind = true;
@@ -323,6 +336,9 @@ static void parse_opts(int argc, char **argv)
                case 'd':
                        cfg_use_dgram = true;
                        break;
+               case 'D':
+                       cfg_drop = true;
+                       break;
                case 'g':
                        cfg_use_gso = true;
                        break;
@@ -367,11 +383,23 @@ static void check_packet_stats(int fd)
        if (getsockopt(fd, SOL_PACKET, PACKET_STATISTICS, &st, &len))
                error(1, errno, "getsockopt packet statistics");
 
-       if (st.tp_packets != 1)
-               error(1, 0, "stats: tp_packets %u != 1", st.tp_packets);
+       if (cfg_drop) {
+               /* PACKET_STATISTICS reports all packets seen (including
+                * drops) in tp_packets
+                */
+               if (st.tp_packets < st.tp_drops)
+                       error(1, 0, "stats: tp_packets %u < tp_drops %u",
+                             st.tp_packets, st.tp_drops);
 
-       if (st.tp_drops != 0)
-               error(1, 0, "stats: tp_drops %u != 0", st.tp_drops);
+               if (st.tp_drops == 0)
+                       error(1, 0, "stats: expected drops but tp_drops == 0");
+       } else {
+               if (st.tp_packets != 1)
+                       error(1, 0, "stats: tp_packets %u != 1", st.tp_packets);
+
+               if (st.tp_drops != 0)
+                       error(1, 0, "stats: tp_drops %u != 0", st.tp_drops);
+       }
 
        /* verify clear on read */
        memset(&st, 0xff, sizeof(st));
@@ -394,7 +422,12 @@ static void run_test(void)
        fdr = setup_rx();
        fds = setup_sniffer();
 
-       total_len = do_tx();
+       total_len = do_tx(cfg_drop);
+
+       if (cfg_drop) {
+               check_packet_stats(fds);
+               goto out;
+       }
 
        /* BPF filter accepts only this length, vlan changes MAC */
        if (cfg_payload_len == DATA_LEN && !cfg_use_vlan) {
@@ -405,6 +438,7 @@ static void run_test(void)
 
        do_rx(fdr, cfg_payload_len, tbuf + total_len - cfg_payload_len);
 
+out:
        if (close(fds))
                error(1, errno, "close s");
        if (close(fdr))
diff --git a/tools/testing/selftests/net/psock_snd.sh 
b/tools/testing/selftests/net/psock_snd.sh
index 1cbfeb5052ec..b6ef12fad5d5 100755
--- a/tools/testing/selftests/net/psock_snd.sh
+++ b/tools/testing/selftests/net/psock_snd.sh
@@ -92,4 +92,9 @@ echo "raw gso max size"
 echo "raw gso max size + 1 (expected to fail)"
 (! ./in_netns.sh ./psock_snd -v -c -g -l "${max_mss_exceeds}")
 
+# test drops statistics
+
+echo "test drops statistics"
+./in_netns.sh ./psock_snd -D
+
 echo "OK. All tests passed"
-- 
2.52.0


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