I don't think it's AF_UNIX alone, I'm getting select() timeout for all family:

./test_progs:udp_redir_to_connected:1775: ingress: read: Timer expired
udp_redir_to_connected:FAIL:1775
#120/36 sockmap_listen/sockmap IPv4 test_udp_redir:FAIL
./test_progs:inet_unix_redir_to_connected:1865: ingress: read: Timer expired
inet_unix_redir_to_connected:FAIL:1865
./test_progs:inet_unix_redir_to_connected:1865: ingress: read: Timer expired
inet_unix_redir_to_connected:FAIL:1865
./test_progs:unix_inet_redir_to_connected:1947: ingress: read: Timer expired
unix_inet_redir_to_connected:FAIL:1947
./test_progs:unix_inet_redir_to_connected:1947: ingress: read: Timer expired
unix_inet_redir_to_connected:FAIL:1947
...
./test_progs:udp_redir_to_connected:1775: ingress: read: Timer expired
udp_redir_to_connected:FAIL:1775
#120/73 sockmap_listen/sockmap IPv6 test_udp_redir:FAIL
./test_progs:inet_unix_redir_to_connected:1865: ingress: read: Timer expired
inet_unix_redir_to_connected:FAIL:1865
./test_progs:inet_unix_redir_to_connected:1865: ingress: read: Timer expired
inet_unix_redir_to_connected:FAIL:1865
./test_progs:unix_inet_redir_to_connected:1947: ingress: read: Timer expired
unix_inet_redir_to_connected:FAIL:1947
./test_progs:unix_inet_redir_to_connected:1947: ingress: read: Timer expired
unix_inet_redir_to_connected:FAIL:1947
#120/74 sockmap_listen/sockmap IPv6 test_udp_unix_redir:FAIL
./test_progs:unix_redir_to_connected:1605: ingress: read: Timer expired
unix_redir_to_connected:FAIL:1605
#120/75 sockmap_listen/sockmap Unix test_unix_redir:FAIL
./test_progs:unix_redir_to_connected:1605: ingress: read: Timer expired
unix_redir_to_connected:FAIL:1605

On Thu, Aug 26, 2021 at 12:07 PM Alexei Starovoitov
[off-list ref] wrote:

On Thu, Aug 26, 2021 at 11:18 AM sunyucong@gmail.com
[off-list ref] wrote:

quoted

Reporting back: I tried a select() based approach, (as attached below)
 but unfortunately it doesn't seem to work. During testing,  I am
always getting full timeout errors as the socket never seems to become
ready to read(). My guess is that this has something to do with the
sockets being created through sockpair() , but I am unable to confirm.

On the other hand, the previous patch approach works perfectly fine, I
would still like to request to apply that instead.

Ok. Applied your earlier patch, but it's a short term workaround.
select() should work for af_unix.
I suspect something got broken with the redirect.
Cong, Jiang,
could you please take a look ?

quoted

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c

b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
index 5c5979046523..247e8b7a6911 100644

--- a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c

@@ -949,7 +949,6 @@ static void redir_to_connected(int family, int

sotype, int sock_mapfd,
        int err, n;
        u32 key;
        char b;
-       int retries = 100;

        zero_verdict_count(verd_mapfd);

@@ -1002,15 +1001,12 @@ static void redir_to_connected(int family, int

sotype, int sock_mapfd,
                goto close_peer1;
        if (pass != 1)
                FAIL("%s: want pass count 1, have %d", log_prefix, pass);
-again:
+
+       if (poll_read(c0, IO_TIMEOUT_SEC))
+             FAIL_ERRNO("%s: read", log_prefix);
        n = read(c0, &b, 1);
-       if (n < 0) {
-               if (errno == EAGAIN && retries--) {
-                       usleep(1000);
-                       goto again;
-               }
+       if (n < 0)
                FAIL_ERRNO("%s: read", log_prefix);
-       }
        if (n == 0)
                FAIL("%s: incomplete read", log_prefix);

@@ -1571,7 +1567,6 @@ static void unix_redir_to_connected(int sotype,

int sock_mapfd,
        const char *log_prefix = redir_mode_str(mode);
        int c0, c1, p0, p1;
        unsigned int pass;
-       int retries = 100;
        int err, n;
        int sfd[2];
        u32 key;

@@ -1606,15 +1601,11 @@ static void unix_redir_to_connected(int

sotype, int sock_mapfd,
        if (pass != 1)
                FAIL("%s: want pass count 1, have %d", log_prefix, pass);

-again:
+       if (poll_read(mode == REDIR_INGRESS ? p0 : c0, IO_TIMEOUT_SEC))
+             FAIL_ERRNO("%s: read", log_prefix);
        n = read(mode == REDIR_INGRESS ? p0 : c0, &b, 1);
-       if (n < 0) {
-               if (errno == EAGAIN && retries--) {
-                       usleep(1000);
-                       goto again;
-               }
+       if (n < 0)
                FAIL_ERRNO("%s: read", log_prefix);
-       }
        if (n == 0)
                FAIL("%s: incomplete read", log_prefix);

@@ -1748,7 +1739,6 @@ static void udp_redir_to_connected(int family,

int sock_mapfd, int verd_mapfd,
        const char *log_prefix = redir_mode_str(mode);
        int c0, c1, p0, p1;
        unsigned int pass;
-       int retries = 100;
        int err, n;
        u32 key;
        char b;

@@ -1781,15 +1771,11 @@ static void udp_redir_to_connected(int family,

int sock_mapfd, int verd_mapfd,
        if (pass != 1)
                FAIL("%s: want pass count 1, have %d", log_prefix, pass);

-again:
+       if (poll_read(mode == REDIR_INGRESS ? p0 : c0, IO_TIMEOUT_SEC * 10))
+               FAIL_ERRNO("%s: read", log_prefix);
        n = read(mode == REDIR_INGRESS ? p0 : c0, &b, 1);
-       if (n < 0) {
-               if (errno == EAGAIN && retries--) {
-                       usleep(1000);
-                       goto again;
-               }
+       if (n < 0)
                FAIL_ERRNO("%s: read", log_prefix);
-       }
        if (n == 0)
                FAIL("%s: incomplete read", log_prefix);

@@ -1841,7 +1827,6 @@ static void inet_unix_redir_to_connected(int

family, int type, int sock_mapfd,
        const char *log_prefix = redir_mode_str(mode);
        int c0, c1, p0, p1;
        unsigned int pass;
-       int retries = 100;
        int err, n;
        int sfd[2];
        u32 key;

@@ -1876,15 +1861,11 @@ static void inet_unix_redir_to_connected(int

family, int type, int sock_mapfd,
        if (pass != 1)
                FAIL("%s: want pass count 1, have %d", log_prefix, pass);

-again:
+       if (poll_read(mode == REDIR_INGRESS ? p0 : c0, IO_TIMEOUT_SEC))
+             FAIL_ERRNO("%s: read", log_prefix);
        n = read(mode == REDIR_INGRESS ? p0 : c0, &b, 1);
-       if (n < 0) {
-               if (errno == EAGAIN && retries--) {
-                       usleep(1000);
-                       goto again;
-               }
+       if (n < 0)
                FAIL_ERRNO("%s: read", log_prefix);
-       }
        if (n == 0)
                FAIL("%s: incomplete read", log_prefix);

@@ -1932,7 +1913,6 @@ static void unix_inet_redir_to_connected(int

family, int type, int sock_mapfd,
        int sfd[2];
        u32 key;
        char b;
-       int retries = 100;

        zero_verdict_count(verd_mapfd);

@@ -1963,15 +1943,11 @@ static void unix_inet_redir_to_connected(int

family, int type, int sock_mapfd,
        if (pass != 1)
                FAIL("%s: want pass count 1, have %d", log_prefix, pass);

-again:
+       if (poll_read(mode == REDIR_INGRESS ? p0 : c0, IO_TIMEOUT_SEC))
+             FAIL_ERRNO("%s: read", log_prefix);
        n = read(mode == REDIR_INGRESS ? p0 : c0, &b, 1);
-       if (n < 0) {
-               if (errno == EAGAIN && retries--) {
-                       usleep(1000);
-                       goto again;
-               }
+       if (n < 0)
                FAIL_ERRNO("%s: read", log_prefix);
-       }
        if (n == 0)
                FAIL("%s: incomplete read", log_prefix);