Re: [PATCH bpf-next] selftests/bpf: reduce more flakyness in sockmap_listen

["sunyucong@xxxxxxxxx" <sunyucong@xxxxxxxxx>]

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.


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);