On Thu, Mar 15, 2018 at 12:03:07AM +0000, Sridhar Pitchai wrote:
> Whenever PCI bus is added, HyperV guarantees the BUS id is unique. Even
"Whenever a PCI bus is added"
> with that when a first device is added to the bus, it overrides bus domain
> ID with the device serial number. Sometime this can result in BUS ID not
Define "Sometime".
> being unique. In this case, when PCI_BUS and a device to bus is added, the
> first device overwrites the bus domain ID to the device serial number,
> which is 0. Since there exsist a PCI bus with domain ID 0 already the PCI
s/exsist/exist
> bus addition fails. This patch make sure when a device is added to a bus,
> it never updated the bus domain ID.
s/updated/updates
> Since we have the transparent SRIOV mode now, the short VF device name
> is no longer needed.
I still do not understand what this means and how it is related to the
patch below, it may be clear to you, it is not to me, at all.
> Fixes: 4a9b0933bdfc("PCI:hv:Use device serial number as PCI domain")
Fixes: 4a9b0933bdfc ("PCI: hv: Use device serial number as PCI domain")
I asked you an explicit question. Commit above was added for a reason
I assume. This patch implies that kernel has been broken since v4.11
which is almost a year ago and nobody every noticed ? Or there are
systems where commit above is _necessary_ and this patch would break
them ?
I want a detailed explanation that highlights *why* it is safe to apply
this patch and send it to stable kernels, commit log above won't do.
Thanks,
Lorenzo
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Sridhar Pitchai <srpitcha@xxxxxxxxxxxxx>
> ---
>
> Changes in v3:
> * fix the commit comment. [KY Srinivasan, Michael Kelley]
> ---
> drivers/pci/host/pci-hyperv.c | 11 -----------
> 1 file changed, 11 deletions(-)
>
> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index 2faf38e..ac67e56 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -1518,17 +1518,6 @@ static struct hv_pci_dev *new_pcichild_device(struct hv_pcibus_device *hbus,
> get_pcichild(hpdev, hv_pcidev_ref_childlist);
> spin_lock_irqsave(&hbus->device_list_lock, flags);
>
> - /*
> - * When a device is being added to the bus, we set the PCI domain
> - * number to be the device serial number, which is non-zero and
> - * unique on the same VM. The serial numbers start with 1, and
> - * increase by 1 for each device. So device names including this
> - * can have shorter names than based on the bus instance UUID.
> - * Only the first device serial number is used for domain, so the
> - * domain number will not change after the first device is added.
> - */
> - if (list_empty(&hbus->children))
> - hbus->sysdata.domain = desc->ser;
> list_add_tail(&hpdev->list_entry, &hbus->children);
> spin_unlock_irqrestore(&hbus->device_list_lock, flags);
> return hpdev;
> --
> 2.7.4
>
