Re: [Qemu-devel] [PATCH v3 08/10] migration: handle the error condition properly

[Xiao Guangrong]

On 08/08/2018 02:56 PM, Peter Xu wrote:
> On Wed, Aug 08, 2018 at 02:29:52PM +0800, Xiao Guangrong wrote:
> > On 08/08/2018 01:08 PM, Peter Xu wrote:
> > > On Tue, Aug 07, 2018 at 05:12:07PM +0800, address@hidden wrote:
> > > > From: Xiao Guangrong <address@hidden>
> > > >
> > > > ram_find_and_save_block() can return negative if any error hanppens,
> > > > however, it is completely ignored in current code
> > >
> > > Could you hint me where we'll return an error?
> >
> > I think control_save_page() may return a error condition but i am not
> > good at it ... Other places look safe _currently_. These functions were
> > designed to have error returned anyway.
>
> Ah, the RDMA codes...
>
> Then I feel like this patch would be more suitable to be put into some
> of the RDMA series - at least we'd better be clear about what errors
> we're going to capture.  For non-RDMA, it seems a bit helpless after
> all - AFAIU we're depending on the few qemu_file_get_error() calls to
> detect output errors.

So, are you talking about to modify the semantic of these functions,
ram_save_host_page(), ram_save_target_page(), etc, and make them
be:
"Returns the number of pages written where zero means no dirty pages,
error conditions are indicated in the QEMUFile @rs->file if it
happened."

If it's what you want, i will update the comments and make the
implementation more clear to reflect this fact for these
functions