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SubjectRe: [PATCH] PCI: hv: Do not wait forever on a device that has disappeared
On Wed, May 23, 2018 at 09:12:01PM +0000, Dexuan Cui wrote:
>
> Before the guest finishes the device initialization, the device can be
> removed anytime by the host, and after that the host won't respond to
> the guest's request, so the guest should be prepared to handle this
> case.
>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> Cc: Stephen Hemminger <sthemmin@microsoft.com>
> Cc: K. Y. Srinivasan <kys@microsoft.com>
> ---
> drivers/pci/host/pci-hyperv.c | 46 ++++++++++++++++++++++++++++++++-----------
> 1 file changed, 34 insertions(+), 12 deletions(-)

Applied with a minor tweak to the commit log to pci/hv for v4.18.

Thanks,
Lorenzo

> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index ad6a64d..248765f 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -556,6 +556,26 @@ static void put_pcichild(struct hv_pci_dev *hv_pcidev,
> static void get_hvpcibus(struct hv_pcibus_device *hv_pcibus);
> static void put_hvpcibus(struct hv_pcibus_device *hv_pcibus);
>
> +/*
> + * There is no good way to get notified from vmbus_onoffer_rescind(),
> + * so let's use polling here, since this is not a hot path.
> + */
> +static int wait_for_response(struct hv_device *hdev,
> + struct completion *comp)
> +{
> + while (true) {
> + if (hdev->channel->rescind) {
> + dev_warn_once(&hdev->device, "The device is gone.\n");
> + return -ENODEV;
> + }
> +
> + if (wait_for_completion_timeout(comp, HZ / 10))
> + break;
> + }
> +
> + return 0;
> +}
> +
> /**
> * devfn_to_wslot() - Convert from Linux PCI slot to Windows
> * @devfn: The Linux representation of PCI slot
> @@ -1569,7 +1589,8 @@ static struct hv_pci_dev *new_pcichild_device(struct hv_pcibus_device *hbus,
> if (ret)
> goto error;
>
> - wait_for_completion(&comp_pkt.host_event);
> + if (wait_for_response(hbus->hdev, &comp_pkt.host_event))
> + goto error;
>
> hpdev->desc = *desc;
> refcount_set(&hpdev->refs, 1);
> @@ -2070,15 +2091,16 @@ static int hv_pci_protocol_negotiation(struct hv_device *hdev)
> sizeof(struct pci_version_request),
> (unsigned long)pkt, VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> + if (!ret)
> + ret = wait_for_response(hdev, &comp_pkt.host_event);
> +
> if (ret) {
> dev_err(&hdev->device,
> - "PCI Pass-through VSP failed sending version reqquest: %#x",
> + "PCI Pass-through VSP failed to request version: %d",
> ret);
> goto exit;
> }
>
> - wait_for_completion(&comp_pkt.host_event);
> -
> if (comp_pkt.completion_status >= 0) {
> pci_protocol_version = pci_protocol_versions[i];
> dev_info(&hdev->device,
> @@ -2287,11 +2309,12 @@ static int hv_pci_enter_d0(struct hv_device *hdev)
> ret = vmbus_sendpacket(hdev->channel, d0_entry, sizeof(*d0_entry),
> (unsigned long)pkt, VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> + if (!ret)
> + ret = wait_for_response(hdev, &comp_pkt.host_event);
> +
> if (ret)
> goto exit;
>
> - wait_for_completion(&comp_pkt.host_event);
> -
> if (comp_pkt.completion_status < 0) {
> dev_err(&hdev->device,
> "PCI Pass-through VSP failed D0 Entry with status %x\n",
> @@ -2331,11 +2354,10 @@ static int hv_pci_query_relations(struct hv_device *hdev)
>
> ret = vmbus_sendpacket(hdev->channel, &message, sizeof(message),
> 0, VM_PKT_DATA_INBAND, 0);
> - if (ret)
> - return ret;
> + if (!ret)
> + ret = wait_for_response(hdev, &comp);
>
> - wait_for_completion(&comp);
> - return 0;
> + return ret;
> }
>
> /**
> @@ -2405,11 +2427,11 @@ static int hv_send_resources_allocated(struct hv_device *hdev)
> size_res, (unsigned long)pkt,
> VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> + if (!ret)
> + ret = wait_for_response(hdev, &comp_pkt.host_event);
> if (ret)
> break;
>
> - wait_for_completion(&comp_pkt.host_event);
> -
> if (comp_pkt.completion_status < 0) {
> ret = -EPROTO;
> dev_err(&hdev->device,
> --
> 2.7.4
>

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