RE: [PATCH v2] PCI: hv: Fix a timing issue which causes kdump to fail occasionally

[Wei Hu]

> -----Original Message-----
> From: Bjorn Helgaas <helgaas@xxxxxxxxxx>
> Sent: Saturday, July 18, 2020 4:11 AM
> To: Wei Hu <weh@xxxxxxxxxxxxx>
> Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang
> <haiyangz@xxxxxxxxxxxxx>; Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>;
> wei.liu@xxxxxxxxxx; lorenzo.pieralisi@xxxxxxx; robh@xxxxxxxxxx;
> bhelgaas@xxxxxxxxxx; linux-hyperv@xxxxxxxxxxxxxxx; linux-
> pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Dexuan Cui
> <decui@xxxxxxxxxxxxx>; Michael Kelley <mikelley@xxxxxxxxxxxxx>
> Subject: Re: [PATCH v2] PCI: hv: Fix a timing issue which causes kdump to fail
> occasionally
> 
> On Fri, Jul 17, 2020 at 10:55:28AM +0800, Wei Hu wrote:
> > Kdump could fail sometime on HyperV guest over Accerlated Network
> > interface. This is because the retry in hv_pci_enter_d0() relies on an
> > asynchronous host event to arrive guest before calling
> > hv_send_resources_allocated(). This fixes the problem by moving retry
> > to hv_pci_probe(), removing this dependence and making the calling
> > sequence synchronous.
> 
> Lorenzo, if you apply this, can you fix this typo?
> 
>   s/Accerlated/Accelerated/
> 
> and maybe even
> 
>   s/HyperV/Hyper-V/
>   s/This fixes the problem/Fix the problem/
>   s/this dependence/this dependency/
> 
> Not sure if "relies on ... event to arrive guest" means "relies on ...
> event arriving in the guest"?  Or maybe "relies on ... event arriving before the
> guest calls ..."?
> 
> This would probably all make perfect sense to me if I understood more about
> Hyper-V :)
> 
> > v2: Adding Fixes tag according to Michael Kelley's review comment.
> 
> There's no need to include this "v2" comment in the commit log.  I think if you
> put it after a line containing only "---" (or maybe "--"?), it will be in the email
> but not in the commit log.
> 
Thanks Bjorn. I will send out a v3 version shortly to correct all these. 
Lorenzo, please pick up my v3 version if you have not started to apply it yet. 

Thanks so much,
Wei