Messages in this thread Patch in this message | | | Date | Thu, 15 Mar 2018 12:05:22 +0000 | From | Lorenzo Pieralisi <> | Subject | Re: [PATCH v3]PCI: hv: fix PCI-BUS domainID corruption |
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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@vger.kernel.org > Signed-off-by: Sridhar Pitchai <srpitcha@microsoft.com> > --- > > 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 >
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