Re: [Qemu-devel] [PATCH] migration: Allow unregister of save_live handlers

[Peter Xu <peterx@redhat.com>]

On Wed, May 24, 2017 at 09:37:19AM +0200, Juan Quintela wrote:
> Migration non save_live handlers have an ops member that is
> dinamically allocated by migration code.  Save_live handlers have it
> passed as argument and are responsability of the caller.  Add a new
> member is_allocated that remembers if ops has to be freed.  This
> allows unregister_savevm() to work with save_live handlers.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  include/migration/vmstate.h | 2 ++
>  migration/savevm.c          | 5 ++++-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index f97411d..1d20e30 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -57,6 +57,8 @@ typedef struct SaveVMHandlers {
>                                uint64_t *non_postcopiable_pending,
>                                uint64_t *postcopiable_pending);
>      LoadStateHandler *load_state;
> +    /* Has been allocated by migratation code */
> +    bool is_allocated;
>  } SaveVMHandlers;
>  
>  int register_savevm(DeviceState *dev,
> diff --git a/migration/savevm.c b/migration/savevm.c
> index d971e5e..187f386 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -628,6 +628,7 @@ int register_savevm(DeviceState *dev,
>      SaveVMHandlers *ops = g_new0(SaveVMHandlers, 1);
>      ops->save_state = save_state;
>      ops->load_state = load_state;
> +    ops->is_allocated = true;
>      return register_savevm_live(dev, idstr, instance_id, version_id,
>                                  ops, opaque);
>  }
> @@ -651,7 +652,9 @@ void unregister_savevm(DeviceState *dev, const char *idstr, void *opaque)
>          if (strcmp(se->idstr, id) == 0 && se->opaque == opaque) {
>              QTAILQ_REMOVE(&savevm_state.handlers, se, entry);
>              g_free(se->compat);
> -            g_free(se->ops);
> +            if (se->ops->is_allocated) {

Would it be good to check against (se->ops && se->ops->is_allocated)?
Since I see that devices registered via
vmstate_register_with_alias_id() won't have this se->ops. I just don't
know whether that case will be allowed to be unregistered with current
function.

Thanks,

> +                g_free(se->ops);
> +            }
>              g_free(se);
>          }
>      }
> -- 
> 2.9.3
> 

-- 
Peter Xu