Re: [PATCH 1/1] yank: Unregister function when using TLS migration

[Lukas Straub]

On Wed, 26 May 2021 17:05:40 -0300
Leonardo Bras <leobras.c@gmail.com> wrote:

> After yank feature was introduced, whenever migration is started using TLS,
> the following error happens in both source and destination hosts:
> 
> (qemu) qemu-kvm: ../util/yank.c:107: yank_unregister_instance:
> Assertion `QLIST_EMPTY(&entry->yankfns)' failed.
> 
> This happens because of a missing yank_unregister_function() when using
> qio-channel-tls.
> 
> Fix this by also allowing TYPE_QIO_CHANNEL_TLS object type to perform
> yank_unregister_function() in channel_close() and multifd_load_cleanup().
> 
> Fixes: 50186051f ("Introduce yank feature")
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1964326
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> ---
>  migration/multifd.c           | 5 +++--
>  migration/qemu-file-channel.c | 7 +++++++
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/multifd.c b/migration/multifd.c
> index 0a4803cfcc..be8656f4c0 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -987,8 +987,9 @@ int multifd_load_cleanup(Error **errp)
>      for (i = 0; i < migrate_multifd_channels(); i++) {
>          MultiFDRecvParams *p = &multifd_recv_state->params[i];
>  
> -        if (object_dynamic_cast(OBJECT(p->c), TYPE_QIO_CHANNEL_SOCKET)
> -            && OBJECT(p->c)->ref == 1) {
> +        if ((object_dynamic_cast(OBJECT(p->c), TYPE_QIO_CHANNEL_SOCKET) ||
> +            (object_dynamic_cast(OBJECT(p->c), TYPE_QIO_CHANNEL_TLS)))  &&
> +            OBJECT(p->c)->ref == 1) {
>              yank_unregister_function(MIGRATION_YANK_INSTANCE,
>                                       migration_yank_iochannel,
>                                       QIO_CHANNEL(p->c));

The code here should be the same as in channel_close. So for the
tls-channel you have to unregister with QIO_CHANNEL(tioc->master) like
below.

Regards,
Lukas Straub

> diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
> index 876d05a540..4f79090f3f 100644
> --- a/migration/qemu-file-channel.c
> +++ b/migration/qemu-file-channel.c
> @@ -26,6 +26,7 @@
>  #include "qemu-file-channel.h"
>  #include "qemu-file.h"
>  #include "io/channel-socket.h"
> +#include "io/channel-tls.h"
>  #include "qemu/iov.h"
>  #include "qemu/yank.h"
>  #include "yank_functions.h"
> @@ -111,6 +112,12 @@ static int channel_close(void *opaque, Error **errp)
>          yank_unregister_function(MIGRATION_YANK_INSTANCE,
>                                   migration_yank_iochannel,
>                                   QIO_CHANNEL(ioc));
> +    } else if (object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_TLS)
> +               && OBJECT(ioc)->ref == 1) {
> +        QIOChannelTLS *tioc = opaque;
> +        yank_unregister_function(MIGRATION_YANK_INSTANCE,
> +                                 migration_yank_iochannel,
> +                                 QIO_CHANNEL(tioc->master));
>      }
>      object_unref(OBJECT(ioc));
>      return ret;



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