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

[Peter Xu <peterx@redhat.com>]

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, guangrong.xiao@gmail.com wrote:
> > > From: Xiao Guangrong <xiaoguangrong@tencent.com>
> > > 
> > > 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.

> 
> > (Anyway I agree that the error handling is not that good, mostly
> >   because the QEMUFile APIs does not provide proper return code, e.g.,
> >   qemu_put_be64 returns void)
> > 
> 
> Yes, it is, the returned error condition is mixed in file's API and
> function's return value... :(
> 

Regards,

-- 
Peter Xu