Re: [PATCH 2/3] migration/postcopy: postpone setting PostcopyState to END

[Dr. David Alan Gilbert]

* Wei Yang (address@hidden) wrote:
> There are two places to call function postcopy_ram_incoming_cleanup()
> 
>     postcopy_ram_listen_thread on migration success
>     loadvm_postcopy_handle_listen one setup failure
> 
> On success, the vm will never accept another migration. On failure,
> PostcopyState is transited from LISTENING to END and would be checked in
> qemu_loadvm_state_main(). If PostcopyState is RUNNING, migration would
> be paused and retried.
> 
> Currently PostcopyState is set to END in function
> postcopy_ram_incoming_cleanup(). With above analysis, we can take this
> step out and postpone this till the end of listen thread to indicate the
> listen thread is done.
> 
> This is a preparation patch for later cleanup.
> 
> Signed-off-by: Wei Yang <address@hidden>

Yes, I think that's OK - I couldn't see anywhere that's currently
checking the state in between.


Reviewed-by: Dr. David Alan Gilbert <address@hidden>

> ---
>  migration/postcopy-ram.c | 2 --
>  migration/savevm.c       | 2 ++
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index a394c7c3a6..5da6de8c8b 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -577,8 +577,6 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState 
> *mis)
>          }
>      }
>  
> -    postcopy_state_set(POSTCOPY_INCOMING_END, NULL);
> -
>      if (mis->postcopy_tmp_page) {
>          munmap(mis->postcopy_tmp_page, mis->largest_page_size);
>          mis->postcopy_tmp_page = NULL;
> diff --git a/migration/savevm.c b/migration/savevm.c
> index eaa4cf58ef..dcad8897a3 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1837,6 +1837,8 @@ static void *postcopy_ram_listen_thread(void *opaque)
>  
>      rcu_unregister_thread();
>      mis->have_listen_thread = false;
> +    postcopy_state_set(POSTCOPY_INCOMING_END, NULL);
> +
>      return NULL;
>  }
>  
> -- 
> 2.17.1
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK