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 <de...@microsoft.com> > Cc: Stephen Hemminger <sthem...@microsoft.com> > Cc: K. Y. Srinivasan <k...@microsoft.com> > --- > drivers/pci/host/pci-hyperv.c | 46 > ++++++++++++++++++++++++++++++++----------- > 1 file changed, 34 insertions(+), 12 deletions(-) > > 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;
This is pretty racy, isn't it ? Also, I reckon you should consider the timeout return value as an error condition unless I am completely missing the point of what you are doing. Lorenzo > +} > + > /** > * 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 > _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel