Re: [Qemu-devel] [PATCH 2/2] tests: add precopy multifd migration with fd protocol

[Peter Xu]

On Thu, Jul 05, 2018 at 01:30:17PM +0530, Balamuruhan S wrote:
> This patch adds test for multifd migration feature with fd protocol.
> 
> Signed-off-by: Balamuruhan S <address@hidden>
> ---
>  tests/migration-test.c | 57 
> ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 57 insertions(+)
> 
> diff --git a/tests/migration-test.c b/tests/migration-test.c
> index e2434e70ea..29ede3810d 100644
> --- a/tests/migration-test.c
> +++ b/tests/migration-test.c
> @@ -10,6 +10,7 @@
>   *
>   */
>  
> +#include <unistd.h>
>  #include "qemu/osdep.h"
>  
>  #include "libqtest.h"
> @@ -202,6 +203,17 @@ static void read_blocktime(QTestState *who)
>      qobject_unref(rsp);
>  }
>  
> +static void getfd(QTestState *who, const char *fdname, int fd)
> +{
> +    QDict *rsp;
> +    gchar *cmd = g_strdup_printf("{ 'execute': 'getfd',"
> +                                 "'arguments': { '%s': '%d'} }", fdname, fd);
> +    rsp = wait_command(who, cmd);

AFAIU Libvirt passes fds to QEMU via the QMP channel using SCM_RIGHTS.
Here we directly specified the fd number. Could you help explain a bit
on how it worked?

> +    g_assert(qdict_haskey(rsp, "return"));
> +    g_free(cmd);
> +    qobject_unref(rsp);
> +}
> +
>  static void wait_for_migration_complete(QTestState *who)
>  {
>      while (true) {
> @@ -619,6 +631,50 @@ static void test_precopy_unix(void)
>      g_free(uri);
>  }
>  
> +static void test_multifd_fd(void)
> +{
> +    int fd[2];
> +
> +    /* create pipe */
> +    if (pipe(fd) == -1)
> +        g_test_message("Skipping test: Unable to create pipe");
> +        return;
> +
> +    /* set uri in target with read fd */
> +    char *uri = g_strdup_printf("fd:%d", fd[0]);
> +    QTestState *from, *to;
> +    test_migrate_start(&from, &to, uri, false);
> +
> +    /* Receive a write file descriptor for source using getfd */
> +    getfd(from, "srcfd", fd[1]);
> +
> +    /* set multifd capability on source and target */
> +    migrate_set_capability(from, "x-multifd", "true");
> +    migrate_set_capability(to, "x-multifd", "true");
> +
> +    /* Wait for the first serial output from the source */
> +    wait_for_serial("src_serial");
> +
> +    /* perform migration */
> +    migrate(from, uri);

I'm not sure I understand correctly here, but I feel like we should
use the fd[1] or anything that was bound to fd[1] on source side to do
the migration rather than fd[0]?  Please feel free to correct me..

Regards,

> +
> +    wait_for_migration_pass(from);
> +
> +    if (!got_stop) {
> +        qtest_qmp_eventwait(from, "STOP");
> +    }
> +    qtest_qmp_eventwait(to, "RESUME");
> +
> +    wait_for_serial("dest_serial");
> +    wait_for_migration_complete(from);
> +    test_migrate_end(from, to, true);
> +    g_free(uri);
> +
> +    /* close the fds */
> +    close(fd[0]);
> +    close(fd[1]);
> +}
> +
>  static void test_multifd_unix(void)
>  {
>      char *uri = g_strdup_printf("unix:%s/migsocket", tmpfs);
> @@ -673,6 +729,7 @@ int main(int argc, char **argv)
>      qtest_add_func("/migration/bad_dest", test_baddest);
>      qtest_add_func("/migration/precopy/unix", test_precopy_unix);
>      qtest_add_func("/migration/multifd/unix", test_multifd_unix);
> +    qtest_add_func("/migration/multifd/fd", test_multifd_fd);
>  
>      ret = g_test_run();
>  
> -- 
> 2.14.3
> 

-- 
Peter Xu