Re: [PATCH V4 18/19] migration-test: cpr-transfer

[Peter Xu]

On Mon, Dec 02, 2024 at 05:20:10AM -0800, Steve Sistare wrote:
> Add a migration test for cpr-transfer mode.  Defer the connection to the
> target monitor, else the test hangs because in cpr-transfer mode QEMU does
> not listen for monitor connections until we send the migrate command to
> source QEMU.
> 
> To test -incoming defer, send a migrate incoming command to the target,
> after sending the migrate command to the source, as required by
> cpr-transfer mode.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  tests/qtest/migration-test.c | 72 
> +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 71 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index 8bc665d..4eb641c 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -1729,6 +1729,7 @@ static void test_precopy_common(MigrateCommon *args)
>  {
>      QTestState *from, *to;
>      void *data_hook = NULL;
> +    const char *connect_uri;
>  
>      if (test_migrate_start(&from, &to, args->listen_uri, &args->start)) {
>          return;
> @@ -1766,11 +1767,16 @@ static void test_precopy_common(MigrateCommon *args)
>          goto finish;
>      }
>  
> -    migrate_qmp(from, to, args->connect_uri, args->connect_channels, "{}");
> +    /* If has channels, then connect_uri is only used for listen defer */
> +    connect_uri = args->connect_channels ? NULL : args->connect_uri;
> +    migrate_qmp(from, to, connect_uri, args->connect_channels, "{}");

This smells like abuse.

If the test case sets connect_uri only because of below...

>  
>      if (args->start.defer_target_connect) {
>          qtest_connect_deferred(to);
>          qtest_qmp_handshake(to);
> +        if (!strcmp(args->listen_uri, "defer")) {
> +            migrate_incoming_qmp(to, args->connect_uri, "{}");

... here, then IMHO it's abusing connect_uri to start service incoming
ports.

We do have solution for "delay" incoming, right?   Shouldn't we use
migrate_get_connect_uri() instead, then never set connect_uri in
cpr-transfer tests?

> +        }
>      }
>  
>      if (args->result != MIG_TEST_SUCCEED) {
> @@ -2415,6 +2421,66 @@ static void 
> test_multifd_file_mapped_ram_fdset_dio(void)
>  }
>  #endif /* !_WIN32 */
>  
> +static void *test_mode_transfer_start(QTestState *from, QTestState *to)
> +{
> +    migrate_set_parameter_str(from, "mode", "cpr-transfer");
> +    return NULL;
> +}
> +
> +/*
> + * cpr-transfer mode cannot use the target monitor prior to starting the
> + * migration, and cannot connect synchronously to the monitor, so defer
> + * the target connection.
> + */
> +static void test_mode_transfer_common(bool incoming_defer)
> +{
> +    g_autofree char *cpr_path = g_strdup_printf("%s/cpr.sock", tmpfs);
> +    g_autofree char *mig_path = g_strdup_printf("%s/migsocket", tmpfs);
> +    g_autofree char *uri = g_strdup_printf("unix:%s", mig_path);
> +
> +    const char *opts = "-machine aux-ram-share=on -nodefaults";
> +    g_autofree char *opts_target = g_strdup_printf(
> +        "-incoming \\{\\\'channel-type\\\':\\\'cpr\\\',"
> +        "\\\'addr\\\':\\{\\\'transport\\\':\\\'socket\\\',"
> +        "\\\'type\\\':\\\'unix\\\',\\\'path\\\':\\\'%s\\\'\\}\\} %s",
> +        cpr_path, opts);

Nobody will be able to change this easily.. Maybe use g_strescape()?

> +
> +    g_autofree char *channels = g_strdup_printf(
> +        "[ { 'channel-type': 'main',"
> +        "    'addr': { 'transport': 'socket',"
> +        "              'type': 'unix',"
> +        "              'path': '%s' } },"
> +        "  { 'channel-type': 'cpr',"
> +        "    'addr': { 'transport': 'socket',"
> +        "              'type': 'unix',"
> +        "              'path': '%s' } } ]",
> +        mig_path, cpr_path);
> +
> +    MigrateCommon args = {
> +        .start.opts_source = opts,
> +        .start.opts_target = opts_target,
> +        .start.defer_target_connect = true,
> +        .start.memory_backend = "-object 
> memory-backend-memfd,id=pc.ram,size=%s"
> +                                " -machine memory-backend=pc.ram",
> +        .listen_uri = incoming_defer ? "defer" : uri,
> +        .connect_uri = incoming_defer ? uri : NULL,
> +        .connect_channels = channels,
> +        .start_hook = test_mode_transfer_start,
> +    };
> +
> +    test_precopy_common(&args);
> +}
> +
> +static void test_mode_transfer(void)
> +{
> +    test_mode_transfer_common(NULL);
> +}
> +
> +static void test_mode_transfer_defer(void)
> +{
> +    test_mode_transfer_common(true);
> +}
> +
>  static void test_precopy_tcp_plain(void)
>  {
>      MigrateCommon args = {
> @@ -3905,6 +3971,10 @@ int main(int argc, char **argv)
>          migration_test_add("/migration/mode/reboot", test_mode_reboot);
>      }
>  
> +    migration_test_add("/migration/mode/transfer", test_mode_transfer);
> +    migration_test_add("/migration/mode/transfer/defer",
> +                       test_mode_transfer_defer);
> +
>      migration_test_add("/migration/precopy/file/mapped-ram",
>                         test_precopy_file_mapped_ram);
>      migration_test_add("/migration/precopy/file/mapped-ram/live",
> -- 
> 1.8.3.1
> 

-- 
Peter Xu