Re: [PATCH v4 8/8] migration: Introduced MigrateChannelList struct to migration code flow.

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, May 12, 2023 at 02:32:40PM +0000, Het Gala wrote:
> Integrated MigrateChannelList with all transport backends (socket, exec
> and rdma) for both source and destination migration code flow.
> 
> Suggested-by: Aravind Retnakaran <aravind.retnakaran@nutanix.com>
> Signed-off-by: Het Gala <het.gala@nutanix.com>
> ---
>  migration/migration.c | 95 +++++++++++++++++++++++++++----------------
>  migration/socket.c    |  5 ++-
>  2 files changed, 64 insertions(+), 36 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index de058643a6..a37eba29e3 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -410,10 +410,11 @@ void migrate_add_address(SocketAddress *address)
>  }
>  
>  static bool migrate_uri_parse(const char *uri,
> -                              MigrateAddress **channel,
> +                              MigrateChannel **channel,
>                                Error **errp)
>  {
>      Error *local_err = NULL;
> +    MigrateChannel *val = g_new0(MigrateChannel, 1);
>      MigrateAddress *addrs = g_new0(MigrateAddress, 1);
>      SocketAddress *saddr;
>      InetSocketAddress *isock = &addrs->u.rdma;
> @@ -441,6 +442,7 @@ static bool migrate_uri_parse(const char *uri,
>      }
>  
>      if (local_err) {
> +        qapi_free_MigrateChannel(val);
>          qapi_free_MigrateAddress(addrs);
>          qapi_free_SocketAddress(saddr);
>          qapi_free_InetSocketAddress(isock);
> @@ -448,7 +450,9 @@ static bool migrate_uri_parse(const char *uri,
>          return false;
>      }
>  
> -    *channel = addrs;
> +    val->channeltype = MIGRATE_CHANNEL_TYPE_MAIN;
> +    val->addr = addrs;
> +    *channel = val;
>      return true;
>  }
>  
> @@ -457,8 +461,9 @@ static void qemu_start_incoming_migration(const char *uri, bool has_channels,
>                                            Error **errp)
>  {
>      Error *local_err = NULL;
> -    MigrateAddress *channel = g_new0(MigrateAddress, 1);
> +    MigrateAddress *addrs;
>      SocketAddress *saddr;
> +    MigrateChannel *channel = NULL;
>  
>      /*
>       * Having preliminary checks for uri and channel
> @@ -467,22 +472,30 @@ static void qemu_start_incoming_migration(const char *uri, bool has_channels,
>          error_setg(errp, "'uri' and 'channels' arguments are mutually "
>                     "exclusive; exactly one of the two should be present in "
>                     "'migrate-incoming' qmp command ");
> -        return;
> -    }
> -
> -    /* URI is not suitable for migration? */
> -    if (!migration_channels_and_uri_compatible(uri, errp)) {
>          goto out;
> -    }
> +    } else if (channels) {
> +        /* To verify that Migrate channel list has only item */
> +        if (channels->next) {
> +            error_setg(errp, "Channel list has more than one entries");
> +            goto out;
> +        }
> +        channel = channels->value;
> +    } else {
> +        /* URI is not suitable for migration? */
> +        if (!migration_channels_and_uri_compatible(uri, errp)) {
> +            goto out;
> +        }

THis check only gets executed when the caller uses the old
URI syntax. We need to it be run when using the modern
MigrateChannel QAPI syntax too.

IOW, migration_channels_and_uri_compatible() needs converting
to take a 'MigrateChannel' object instead of URI, and then
the check can be run after the URI -> MigrateCHannel conversion

>  
> -    if (uri && !migrate_uri_parse(uri, &channel, errp)) {
> -        error_setg(errp, "Error parsing uri");
> -        goto out;
> +        if (uri && !migrate_uri_parse(uri, &channel, errp)) {
> +            error_setg(errp, "Error parsing uri");
> +            goto out;
> +        }
>      }
>  
> -    saddr = &channel->u.socket;
> +    addrs = channel->addr;
> +    saddr = &channel->addr->u.socket;
>      qapi_event_send_migration(MIGRATION_STATUS_SETUP);
> -    if (channel->transport == MIGRATE_TRANSPORT_SOCKET) {
> +    if (addrs->transport == MIGRATE_TRANSPORT_SOCKET) {
>          if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
>              saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
>              saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
> @@ -491,23 +504,25 @@ static void qemu_start_incoming_migration(const char *uri, bool has_channels,
>              fd_start_incoming_migration(saddr->u.fd.str, &local_err);
>          }
>  #ifdef CONFIG_RDMA
> -    } else if (channel->transport == MIGRATE_TRANSPORT_RDMA) {
> -        rdma_start_incoming_migration(&channel->u.rdma, &local_err);
> +    } else if (addrs->transport == MIGRATE_TRANSPORT_RDMA) {
> +        rdma_start_incoming_migration(&addrs->u.rdma, &local_err);
>  #endif
> -    } else if (channel->transport == MIGRATE_TRANSPORT_EXEC) {
> -        exec_start_incoming_migration(channel->u.exec.args, &local_err);
> +    } else if (addrs->transport == MIGRATE_TRANSPORT_EXEC) {
> +        exec_start_incoming_migration(addrs->u.exec.args, &local_err);
>      } else {
>          error_setg(errp, "unknown migration protocol: %s", uri);
>      }
>  
>      if (local_err) {
> +        qapi_free_MigrateAddress(addrs);
>          qapi_free_SocketAddress(saddr);
>          error_propagate(errp, local_err);
>          return;
>      }
>  
>  out:
> -    qapi_free_MigrateAddress(channel);
> +    qapi_free_MigrateChannel(channel);
> +    return;
>  }
>  
>  static void process_incoming_migration_bh(void *opaque)
> @@ -1714,8 +1729,9 @@ void qmp_migrate(const char *uri, bool has_channels,
>  {
>      Error *local_err = NULL;
>      MigrationState *s = migrate_get_current();
> -    MigrateAddress *channel = g_new0(MigrateAddress, 1);
> +    MigrateAddress *addrs;
>      SocketAddress *saddr;
> +    MigrateChannel *channel = NULL;
>  
>      /*
>       * Having preliminary checks for uri and channel
> @@ -1724,17 +1740,24 @@ void qmp_migrate(const char *uri, bool has_channels,
>          error_setg(errp, "'uri' and 'channels' arguments are mutually "
>                     "exclusive; exactly one of the two should be present in "
>                     "'migrate' qmp command ");
> -        return;
> -    }
> -
> -    /* URI is not suitable for migration? */
> -    if (!migration_channels_and_uri_compatible(uri, errp)) {
>          goto out;
> -    }
> +    } else if (channels) {
> +        /* To verify that Migrate channel list has only item */
> +        if (channels->next) {
> +            error_setg(errp, "Channel list has more than one entries");
> +            goto out;
> +        }
> +        channel = channels->value;
> +    } else {
> +        /* URI is not suitable for migration? */
> +        if (!migration_channels_and_uri_compatible(uri, errp)) {
> +            goto out;
> +        }
>  
> -    if (!migrate_uri_parse(uri, &channel, &local_err)) {
> -        error_setg(errp, "Error parsing uri");
> -        goto out;
> +        if (!migrate_uri_parse(uri, &channel, &local_err)) {
> +            error_setg(errp, "Error parsing uri");
> +            goto out;
> +        }
>      }
>  
>      if (!migrate_prepare(s, has_blk && blk, has_inc && inc,
> @@ -1749,8 +1772,9 @@ void qmp_migrate(const char *uri, bool has_channels,
>          }
>      }
>  
> -    saddr = &channel->u.socket;
> -    if (channel->transport == MIGRATE_TRANSPORT_SOCKET) {
> +    addrs = channel->addr;
> +    saddr = &channel->addr->u.socket;
> +    if (addrs->transport == MIGRATE_TRANSPORT_SOCKET) {
>          if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
>              saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
>              saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
> @@ -1759,11 +1783,11 @@ void qmp_migrate(const char *uri, bool has_channels,
>              fd_start_outgoing_migration(s, saddr->u.fd.str, &local_err);
>          }
>  #ifdef CONFIG_RDMA
> -    } else if (channel->transport == MIGRATE_TRANSPORT_RDMA) {
> -        rdma_start_outgoing_migration(s, &channel->u.rdma, &local_err);
> +    } else if (addrs->transport == MIGRATE_TRANSPORT_RDMA) {
> +        rdma_start_outgoing_migration(s, &addrs->u.rdma, &local_err);
>  #endif
> -    } else if (channel->transport == MIGRATE_TRANSPORT_EXEC) {
> -        exec_start_outgoing_migration(s, channel->u.exec.args, &local_err);
> +    } else if (addrs->transport == MIGRATE_TRANSPORT_EXEC) {
> +        exec_start_outgoing_migration(s, addrs->u.exec.args, &local_err);
>      } else {
>          if (!(has_resume && resume)) {
>              yank_unregister_instance(MIGRATION_YANK_INSTANCE);
> @@ -1780,6 +1804,7 @@ void qmp_migrate(const char *uri, bool has_channels,
>          if (!(has_resume && resume)) {
>              yank_unregister_instance(MIGRATION_YANK_INSTANCE);
>          }
> +        qapi_free_MigrateAddress(addrs);
>          qapi_free_SocketAddress(saddr);
>          migrate_fd_error(s, local_err);
>          error_propagate(errp, local_err);
> diff --git a/migration/socket.c b/migration/socket.c
> index 8e7430b266..98e3ea1514 100644
> --- a/migration/socket.c
> +++ b/migration/socket.c
> @@ -28,6 +28,8 @@
>  #include "trace.h"
>  #include "postcopy-ram.h"
>  #include "options.h"
> +#include "qapi/clone-visitor.h"
> +#include "qapi/qapi-visit-sockets.h"
>  
>  struct SocketOutgoingArgs {
>      SocketAddress *saddr;
> @@ -114,12 +116,13 @@ void socket_start_outgoing_migration(MigrationState *s,
>  {
>      QIOChannelSocket *sioc = qio_channel_socket_new();
>      struct SocketConnectData *data = g_new0(struct SocketConnectData, 1);
> +    SocketAddress *addr = QAPI_CLONE(SocketAddress, saddr);
>  
>      data->s = s;
>  
>      /* in case previous migration leaked it */
>      qapi_free_SocketAddress(outgoing_args.saddr);
> -    outgoing_args.saddr = saddr;
> +    outgoing_args.saddr = addr;
>  
>      if (saddr->type == SOCKET_ADDRESS_TYPE_INET) {
>          data->hostname = g_strdup(saddr->u.inet.host);
> -- 
> 2.22.3
> 

With regards,
Daniel
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