RE: [PATCH v3] PCI: hv: Fix a timing issue which causes kdump to fail occasionally

[Michael Kelley]

From: Wei Hu <weh@xxxxxxxxxxxxx> Sent: Friday, July 17, 2020 8:48 PM
> To: 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>
> Cc: Wei Hu <weh@xxxxxxxxxxxxx>
> Subject: [PATCH v3] PCI: hv: Fix a timing issue which causes kdump to fail occasionally
> 
> Kdump could fail sometime on Hyper-V guest over Accelerated Network
> interface. This is because the retry in hv_pci_enter_d0() relies on
> an asynchronous host event arriving before the guest calls
> hv_send_resources_allocated(). Fix the problem by moving retry
> to hv_pci_probe(), removing this dependency and making the calling
> sequence synchronous.
> 
> Fixes: c81992e7f4aa ("PCI: hv: Retry PCI bus D0 entry on invalid device state")
> Signed-off-by: Wei Hu <weh@xxxxxxxxxxxxx>
> ---
>     v2: Adding Fixes tag according to Michael Kelley's review comment.
>     v3: Fix couple typos and reword commit message to make it clearer.
>     Thanks the comments from Bjorn Helgaas.
> 
>  drivers/pci/controller/pci-hyperv.c | 66 ++++++++++++++---------------
>  1 file changed, 32 insertions(+), 34 deletions(-)
> 

I gave my Reviewed-by on the earlier v1 of this patch, but reiterating it
here:

Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>