Re: [PATCH 14/20] migration: remove the QEMUFileOps 'shut_down' callback

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

* Daniel P. Berrangé (berrange@redhat.com) wrote:
> On Thu, Jun 09, 2022 at 05:12:41PM +0100, Dr. David Alan Gilbert wrote:
> > * Daniel P. Berrangé (berrange@redhat.com) wrote:
> > > This directly implements the shutdown logic using QIOChannel APIs.
> > > 
> > > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> > > ---
> > >  migration/qemu-file-channel.c | 27 ---------------------------
> > >  migration/qemu-file.c         | 10 +++++++---
> > >  migration/qemu-file.h         | 10 ----------
> > >  3 files changed, 7 insertions(+), 40 deletions(-)
> > > 
> > > diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
> > > index 5cb8ac93c0..80f05dc371 100644
> > > --- a/migration/qemu-file-channel.c
> > > +++ b/migration/qemu-file-channel.c
> > > @@ -112,31 +112,6 @@ static int channel_close(void *opaque, Error **errp)
> > >  }
> > >  
> > >  
> > > -static int channel_shutdown(void *opaque,
> > > -                            bool rd,
> > > -                            bool wr,
> > > -                            Error **errp)
> > > -{
> > > -    QIOChannel *ioc = QIO_CHANNEL(opaque);
> > > -
> > > -    if (qio_channel_has_feature(ioc,
> > > -                                QIO_CHANNEL_FEATURE_SHUTDOWN)) {
> > > -        QIOChannelShutdown mode;
> > > -        if (rd && wr) {
> > > -            mode = QIO_CHANNEL_SHUTDOWN_BOTH;
> > > -        } else if (rd) {
> > > -            mode = QIO_CHANNEL_SHUTDOWN_READ;
> > > -        } else {
> > > -            mode = QIO_CHANNEL_SHUTDOWN_WRITE;
> > > -        }
> > > -        if (qio_channel_shutdown(ioc, mode, errp) < 0) {
> > > -            return -EIO;
> > > -        }
> > > -    }
> > > -    return 0;
> > > -}
> > > -
> > > -
> > >  static int channel_set_blocking(void *opaque,
> > >                                  bool enabled,
> > >                                  Error **errp)
> > > @@ -166,7 +141,6 @@ static QEMUFile *channel_get_output_return_path(void *opaque)
> > >  static const QEMUFileOps channel_input_ops = {
> > >      .get_buffer = channel_get_buffer,
> > >      .close = channel_close,
> > > -    .shut_down = channel_shutdown,
> > >      .set_blocking = channel_set_blocking,
> > >      .get_return_path = channel_get_input_return_path,
> > >  };
> > > @@ -175,7 +149,6 @@ static const QEMUFileOps channel_input_ops = {
> > >  static const QEMUFileOps channel_output_ops = {
> > >      .writev_buffer = channel_writev_buffer,
> > >      .close = channel_close,
> > > -    .shut_down = channel_shutdown,
> > >      .set_blocking = channel_set_blocking,
> > >      .get_return_path = channel_get_output_return_path,
> > >  };
> > > diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> > > index 5548e1abf3..fd9f060c02 100644
> > > --- a/migration/qemu-file.c
> > > +++ b/migration/qemu-file.c
> > > @@ -74,13 +74,17 @@ struct QEMUFile {
> > >   */
> > >  int qemu_file_shutdown(QEMUFile *f)
> > >  {
> > > -    int ret;
> > > +    int ret = 0;
> > >  
> > >      f->shutdown = true;
> > > -    if (!f->ops->shut_down) {
> > > +    if (!qio_channel_has_feature(f->ioc,
> > > +                                 QIO_CHANNEL_FEATURE_SHUTDOWN)) {
> > >          return -ENOSYS;
> > >      }
> > > -    ret = f->ops->shut_down(f->ioc, true, true, NULL);
> > > +
> > > +    if (qio_channel_shutdown(f->ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL) < 0) {
> > > +        ret = -EIO;
> > > +    }
> > 
> > OK, so this is following the code you're flattening; so:
> > 
> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > 
> >  I wonder if there's any reason it doesn't just pass the return value through to ret rather
> > than flattening it to -EIO?
> 
> qio methods never return errno values just positive integer or -1.
> 
> Since qemu_file_shutdown seems to want an errno, I picked EIO
> 
> Better would be for qemu_file_shutdown to have an Error **errp
> param instead but that could come later.

Ah OK.

Dave

> 
> With regards,
> Daniel
> -- 
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> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK