Re: [PATCH v3 1/1] yank: Unregister function when using TLS migration

[Dr. David Alan Gilbert]

cc'ing in qemu-stable - I think we'd probably want this on 6.0
(It's currently merged as 7de2e8565335c13fb3516cddbe2e40e366cce273 ).
Although you'll probably also want the missing dependency fix
Philippe is working (See: 
Mathieu- ( 42) [RFC PATCH] migration: Add missing dependency on GNUTLS )

Dave

* Leonardo Bras (leobras.c@gmail.com) wrote:
> After yank feature was introduced in migration, 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().
> 
> Also, inside migration_channel_connect() and
> migration_channel_process_incoming() move yank_register_function() so
> it only runs once on a TLS migration.
> 
> Fixes: b5eea99ec2f ("migration: Add yank feature", 2021-01-13)
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1964326
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> 
> --
> Changes since v2:
> - Dropped all references to ioc->master
> - yank_register_function() and yank_unregister_function() now only run
>   once in a TLS migration.
> 
> Changes since v1:
> - Cast p->c to QIOChannelTLS into multifd_load_cleanup()
> ---
>  migration/channel.c           | 26 ++++++++++++++------------
>  migration/multifd.c           |  3 ++-
>  migration/qemu-file-channel.c |  4 +++-
>  3 files changed, 19 insertions(+), 14 deletions(-)
> 
> diff --git a/migration/channel.c b/migration/channel.c
> index c9ee902021..01275a9162 100644
> --- a/migration/channel.c
> +++ b/migration/channel.c
> @@ -38,18 +38,19 @@ void migration_channel_process_incoming(QIOChannel *ioc)
>      trace_migration_set_incoming_channel(
>          ioc, object_get_typename(OBJECT(ioc)));
>  
> -    if (object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET)) {
> -        yank_register_function(MIGRATION_YANK_INSTANCE,
> -                               migration_yank_iochannel,
> -                               QIO_CHANNEL(ioc));
> -    }
> -
>      if (s->parameters.tls_creds &&
>          *s->parameters.tls_creds &&
>          !object_dynamic_cast(OBJECT(ioc),
>                               TYPE_QIO_CHANNEL_TLS)) {
>          migration_tls_channel_process_incoming(s, ioc, &local_err);
>      } else {
> +        if (object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET) ||
> +            object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_TLS)) {
> +            yank_register_function(MIGRATION_YANK_INSTANCE,
> +                                   migration_yank_iochannel,
> +                                   QIO_CHANNEL(ioc));
> +        }
> +
>          migration_ioc_process_incoming(ioc, &local_err);
>      }
>  
> @@ -76,12 +77,6 @@ void migration_channel_connect(MigrationState *s,
>          ioc, object_get_typename(OBJECT(ioc)), hostname, error);
>  
>      if (!error) {
> -        if (object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET)) {
> -            yank_register_function(MIGRATION_YANK_INSTANCE,
> -                                   migration_yank_iochannel,
> -                                   QIO_CHANNEL(ioc));
> -        }
> -
>          if (s->parameters.tls_creds &&
>              *s->parameters.tls_creds &&
>              !object_dynamic_cast(OBJECT(ioc),
> @@ -99,6 +94,13 @@ void migration_channel_connect(MigrationState *s,
>          } else {
>              QEMUFile *f = qemu_fopen_channel_output(ioc);
>  
> +            if (object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET) ||
> +                object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_TLS)) {
> +                yank_register_function(MIGRATION_YANK_INSTANCE,
> +                                       migration_yank_iochannel,
> +                                       QIO_CHANNEL(ioc));
> +            }
> +
>              qemu_mutex_lock(&s->qemu_file_lock);
>              s->to_dst_file = f;
>              qemu_mutex_unlock(&s->qemu_file_lock);
> diff --git a/migration/multifd.c b/migration/multifd.c
> index 0a4803cfcc..2e8f001bc0 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -987,7 +987,8 @@ 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)
> +        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,
> diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
> index 876d05a540..fad340ea7a 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"
> @@ -106,7 +107,8 @@ static int channel_close(void *opaque, Error **errp)
>      int ret;
>      QIOChannel *ioc = QIO_CHANNEL(opaque);
>      ret = qio_channel_close(ioc, errp);
> -    if (object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET)
> +    if ((object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET) ||
> +         object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_TLS))
>          && OBJECT(ioc)->ref == 1) {
>          yank_unregister_function(MIGRATION_YANK_INSTANCE,
>                                   migration_yank_iochannel,
> -- 
> 2.31.1
> 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK