Re: [PATCH V4 07/11] tests/qtest: migration events

[Peter Xu <peterx@redhat.com>]

On Tue, Aug 29, 2023 at 11:18:02AM -0700, Steve Sistare wrote:
> Define a state object to capture events seen by migration tests, to allow
> more events to be captured in a subsequent patch, and simplify event
> checking in wait_for_migration_pass.  No functional change.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> Reviewed-by: Fabiano Rosas <farosas@suse.de>
> ---
>  tests/qtest/migration-helpers.c | 24 +++++----------
>  tests/qtest/migration-helpers.h |  8 +++--
>  tests/qtest/migration-test.c    | 68 +++++++++++++++++++----------------------
>  3 files changed, 44 insertions(+), 56 deletions(-)
> 
> diff --git a/tests/qtest/migration-helpers.c b/tests/qtest/migration-helpers.c
> index be00c52..b541108 100644
> --- a/tests/qtest/migration-helpers.c
> +++ b/tests/qtest/migration-helpers.c
> @@ -23,26 +23,16 @@
>   */
>  #define MIGRATION_STATUS_WAIT_TIMEOUT 120
>  
> -bool migrate_watch_for_stop(QTestState *who, const char *name,
> -                            QDict *event, void *opaque)
> -{
> -    bool *seen = opaque;
> -
> -    if (g_str_equal(name, "STOP")) {
> -        *seen = true;
> -        return true;
> -    }
> -
> -    return false;
> -}
> -
> -bool migrate_watch_for_resume(QTestState *who, const char *name,
> +bool migrate_watch_for_events(QTestState *who, const char *name,
>                                QDict *event, void *opaque)
>  {
> -    bool *seen = opaque;
> +    QTestMigrationState *state = opaque;
>  
> -    if (g_str_equal(name, "RESUME")) {
> -        *seen = true;
> +    if (g_str_equal(name, "STOP")) {
> +        state->stop_seen = true;
> +        return true;
> +    } else if (g_str_equal(name, "RESUME")) {
> +        state->resume_seen = true;
>          return true;
>      }
>  
> diff --git a/tests/qtest/migration-helpers.h b/tests/qtest/migration-helpers.h
> index 009e250..59fbb83 100644
> --- a/tests/qtest/migration-helpers.h
> +++ b/tests/qtest/migration-helpers.h
> @@ -15,9 +15,11 @@
>  
>  #include "libqtest.h"
>  
> -bool migrate_watch_for_stop(QTestState *who, const char *name,
> -                            QDict *event, void *opaque);
> -bool migrate_watch_for_resume(QTestState *who, const char *name,
> +typedef struct QTestMigrationState {
> +    bool stop_seen, resume_seen;
> +} QTestMigrationState;
> +
> +bool migrate_watch_for_events(QTestState *who, const char *name,
>                                QDict *event, void *opaque);
>  
>  G_GNUC_PRINTF(3, 4)
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index 62d3f37..526a1b7 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -43,8 +43,8 @@
>  unsigned start_address;
>  unsigned end_address;
>  static bool uffd_feature_thread_id;
> -static bool got_src_stop;
> -static bool got_dst_resume;
> +static QTestMigrationState src_state;
> +static QTestMigrationState dst_state;
>  
>  /*
>   * An initial 3 MB offset is used as that corresponds
> @@ -188,6 +188,13 @@ static void wait_for_serial(const char *side)
>      } while (true);
>  }
>  
> +static void wait_for_stop(QTestState *who, QTestMigrationState *state)
> +{
> +    if (!state->stop_seen) {
> +        qtest_qmp_eventwait(who, "STOP");
> +    }
> +}
> +
>  /*
>   * It's tricky to use qemu's migration event capability with qtest,
>   * events suddenly appearing confuse the qmp()/hmp() responses.
> @@ -235,21 +242,19 @@ static void read_blocktime(QTestState *who)
>      qobject_unref(rsp_return);
>  }
>  
> +/*
> + * Wait for two changes in the migration pass count, but bail if we stop.
> + */
>  static void wait_for_migration_pass(QTestState *who)
>  {
> -    uint64_t initial_pass = get_migration_pass(who);
> -    uint64_t pass;
> +    uint64_t pass, prev_pass = 0, changes = 0;
>  
> -    /* Wait for the 1st sync */
> -    while (!got_src_stop && !initial_pass) {
> -        usleep(1000);
> -        initial_pass = get_migration_pass(who);
> -    }
> -
> -    do {
> +    while (changes < 2 && !src_state.stop_seen) {
>          usleep(1000);
>          pass = get_migration_pass(who);
> -    } while (pass == initial_pass && !got_src_stop);
> +        changes += (pass != prev_pass);
> +        prev_pass = pass;
> +    }

Here won't it start to wait for 2 iterations every time instead of 1?

Note that previously we only wait for 1 iteration as long as not the
initial pass.  And I think the change will double the counts for below..

            while (args->iterations > 1) {
                wait_for_migration_pass(from);
                args->iterations--;
            }

The event-related changes are all fine, but maybe leave this piece as before?

>  }
>  
>  static void check_guests_ram(QTestState *who)
> @@ -586,10 +591,7 @@ static void migrate_postcopy_start(QTestState *from, QTestState *to)
>  {
>      qtest_qmp_assert_success(from, "{ 'execute': 'migrate-start-postcopy' }");
>  
> -    if (!got_src_stop) {
> -        qtest_qmp_eventwait(from, "STOP");
> -    }
> -
> +    wait_for_stop(from, &src_state);
>      qtest_qmp_eventwait(to, "RESUME");
>  }
>  
> @@ -720,8 +722,9 @@ static int test_migrate_start(QTestState **from, QTestState **to,
>          }
>      }
>  
> -    got_src_stop = false;
> -    got_dst_resume = false;
> +    dst_state = (QTestMigrationState) { };
> +    src_state = (QTestMigrationState) { };
> +
>      bootpath = g_strdup_printf("%s/bootsect", tmpfs);
>      if (strcmp(arch, "i386") == 0 || strcmp(arch, "x86_64") == 0) {
>          /* the assembled x86 boot sector should be exactly one sector large */
> @@ -801,8 +804,8 @@ static int test_migrate_start(QTestState **from, QTestState **to,
>      if (!args->only_target) {
>          *from = qtest_init(cmd_source);
>          qtest_qmp_set_event_callback(*from,
> -                                     migrate_watch_for_stop,
> -                                     &got_src_stop);
> +                                     migrate_watch_for_events,
> +                                     &src_state);
>      }
>  
>      cmd_target = g_strdup_printf("-accel kvm%s -accel tcg "
> @@ -821,8 +824,8 @@ static int test_migrate_start(QTestState **from, QTestState **to,
>                                   ignore_stderr);
>      *to = qtest_init(cmd_target);
>      qtest_qmp_set_event_callback(*to,
> -                                 migrate_watch_for_resume,
> -                                 &got_dst_resume);
> +                                 migrate_watch_for_events,
> +                                 &dst_state);
>  
>      /*
>       * Remove shmem file immediately to avoid memory leak in test failed case.
> @@ -1516,9 +1519,7 @@ static void test_precopy_common(MigrateCommon *args)
>           */
>          if (args->result == MIG_TEST_SUCCEED) {
>              qtest_qmp_assert_success(from, "{ 'execute' : 'stop'}");
> -            if (!got_src_stop) {
> -                qtest_qmp_eventwait(from, "STOP");
> -            }
> +            wait_for_stop(from, &src_state);
>              migrate_ensure_converge(from);
>          }
>      }
> @@ -1560,9 +1561,8 @@ static void test_precopy_common(MigrateCommon *args)
>               */
>              wait_for_migration_complete(from);
>  
> -            if (!got_src_stop) {
> -                qtest_qmp_eventwait(from, "STOP");
> -            }
> +            wait_for_stop(from, &src_state);
> +
>          } else {
>              wait_for_migration_complete(from);
>              /*
> @@ -1575,7 +1575,7 @@ static void test_precopy_common(MigrateCommon *args)
>              qtest_qmp_assert_success(to, "{ 'execute' : 'cont'}");
>          }
>  
> -        if (!got_dst_resume) {
> +        if (!dst_state.resume_seen) {
>              qtest_qmp_eventwait(to, "RESUME");
>          }
>  
> @@ -1696,9 +1696,7 @@ static void test_ignore_shared(void)
>  
>      migrate_wait_for_dirty_mem(from, to);
>  
> -    if (!got_src_stop) {
> -        qtest_qmp_eventwait(from, "STOP");
> -    }
> +    wait_for_stop(from, &src_state);
>  
>      qtest_qmp_eventwait(to, "RESUME");
>  
> @@ -2139,7 +2137,7 @@ static void test_migrate_auto_converge(void)
>              break;
>          }
>          usleep(20);
> -        g_assert_false(got_src_stop);
> +        g_assert_false(src_state.stop_seen);
>      } while (true);
>      /* The first percentage of throttling should be at least init_pct */
>      g_assert_cmpint(percentage, >=, init_pct);
> @@ -2481,9 +2479,7 @@ static void test_multifd_tcp_cancel(void)
>  
>      migrate_ensure_converge(from);
>  
> -    if (!got_src_stop) {
> -        qtest_qmp_eventwait(from, "STOP");
> -    }
> +    wait_for_stop(from, &src_state);
>      qtest_qmp_eventwait(to2, "RESUME");
>  
>      wait_for_serial("dest_serial");
> -- 
> 1.8.3.1
> 

-- 
Peter Xu