Re: [Qemu-devel] [PATCH] migration/fd: abort migration if receive POLLHUP event

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Wang Xin (wangxinxin.wang@huawei.com) wrote:
> If the fd socket peer closed shortly, ppoll may receive a POLLHUP
> event before the expected POLLIN event, and qemu will do nothing
> but goes into an infinite loop of the POLLHUP event.
> 
> So, abort the migration if we receive a POLLHUP event.

Hi Wang Xin,
  Can you explain how you manage to trigger this case; I've not hit it.

> Signed-off-by: Wang Xin <wangxinxin.wang@huawei.com>
> 
> diff --git a/migration/fd.c b/migration/fd.c
> index cd06182..5932c87 100644
> --- a/migration/fd.c
> +++ b/migration/fd.c
> @@ -15,6 +15,7 @@
>   */
>  
>  #include "qemu/osdep.h"
> +#include "qemu/error-report.h"
>  #include "channel.h"
>  #include "fd.h"
>  #include "monitor/monitor.h"
> @@ -46,6 +47,11 @@ static gboolean fd_accept_incoming_migration(QIOChannel *ioc,
>                                               GIOCondition condition,
>                                               gpointer opaque)
>  {
> +    if (condition & G_IO_HUP) {
> +        error_report("The migration peer closed, job abort");
> +        exit(EXIT_FAILURE);
> +    }
> +

OK,  I wish we had a nicer way for failing;  especially for the
multifd/postcopy recovery worlds where one failed connection might not
be fatal; but I don't see how to do that here.

>      migration_channel_process_incoming(ioc);
>      object_unref(OBJECT(ioc));
>      return G_SOURCE_REMOVE;
> @@ -67,7 +73,7 @@ void fd_start_incoming_migration(const char *infd, Error **errp)
>  
>      qio_channel_set_name(QIO_CHANNEL(ioc), "migration-fd-incoming");
>      qio_channel_add_watch(ioc,
> -                          G_IO_IN,
> +                          G_IO_IN | G_IO_HUP,
>                            fd_accept_incoming_migration,
>                            NULL,
>                            NULL);

Dave

> -- 
> 2.8.1.windows.1
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK