Re: [PATCH V6 11/14] tests/qtest: precopy migration with suspend

[Peter Xu <peterx@redhat.com>]

On Tue, Dec 05, 2023 at 11:14:43AM -0500, Steven Sistare wrote:
> Calling migrate_wait_for_dirty_mem proves that a source write is propagated
> to the dest, even for the suspended case.  We fully expect that, but a good 
> test verifies our expectations.  That is done in the first loop of 
> migrate_wait_for_dirty_mem.  After that, we must check for the suspended 
> state, because the second loop will not terminate.  Here is a more explicit
> version:
> 
> static void migrate_wait_for_dirty_mem(QTestState *from,
>                                        QTestState *to)
> {
>     uint64_t watch_address = start_address + MAGIC_OFFSET_BASE;
>     uint64_t marker_address = start_address + MAGIC_OFFSET;
>     uint8_t watch_byte;
> 
>     /*
>      * Wait for the MAGIC_MARKER to get transferred, as an
>      * indicator that a migration pass has made some known
>      * amount of progress.
>      */
>     do {
>         usleep(1000 * 10);
>     } while (qtest_readq(to, marker_address) != MAGIC_MARKER);
> 
> +    /* If suspended, src only iterates once, and watch_byte may never change */
> +    if (src_state.suspend_me) {
> +        return;
> +    }

Ok.

> Yes, it played that role.  I will delete all the existing calls to wait_for_suspended,
> and add them after wait_for_serial("src_serial") in test_precopy_common and
> migrate_postcopy_prepare.

Sounds good.

-- 
Peter Xu