PCI: hv: Fix hv_pci_remove() for hot-remove

1. We don't really need such a big on-stack buffer when sending the
teardown_packet: vmbus_sendpacket() here only uses sizeof(struct
pci_message).

2. In the hot-remove case (PCI_EJECT), after we send PCI_EJECTION_COMPLETE
to the host, the host will send a RESCIND_CHANNEL message to us and the
host won't access the per-channel ringbuffer any longer, so we needn't send
PCI_RESOURCES_RELEASED/PCI_BUS_D0EXIT to the host, and we shouldn't expect
the host's completion message of PCI_BUS_D0EXIT, which will never come.

3. We should send PCI_BUS_D0EXIT after hv_send_resources_released().

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jake Oshins <jakeo@microsoft.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
CC: Haiyang Zhang <haiyangz@microsoft.com>
CC: Vitaly Kuznetsov <vkuznets@redhat.com>

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 9ea63b4b0e5876dee5932a0b470ad11537902181..b1747469a32c3d67d057eb937ec6d7fc5a6e947e 100644 (file)
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -2266,24 +2266,32 @@ free_bus:
        return ret;
 }
 
-/**
- * hv_pci_remove() - Remove routine for this VMBus channel
- * @hdev:      VMBus's tracking struct for this root PCI bus
- *
- * Return: 0 on success, -errno on failure
- */
-static int hv_pci_remove(struct hv_device *hdev)
+static void hv_pci_bus_exit(struct hv_device *hdev)
 {
-       int ret;
-       struct hv_pcibus_device *hbus;
-       union {
+       struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+       struct {
                struct pci_packet teardown_packet;
-               u8 buffer[0x100];
+               u8 buffer[sizeof(struct pci_message)];
        } pkt;
        struct pci_bus_relations relations;
        struct hv_pci_compl comp_pkt;
+       int ret;
 
-       hbus = hv_get_drvdata(hdev);
+       /*
+        * After the host sends the RESCIND_CHANNEL message, it doesn't
+        * access the per-channel ringbuffer any longer.
+        */
+       if (hdev->channel->rescind)
+               return;
+
+       /* Delete any children which might still exist. */
+       memset(&relations, 0, sizeof(relations));
+       hv_pci_devices_present(hbus, &relations);
+
+       ret = hv_send_resources_released(hdev);
+       if (ret)
+               dev_err(&hdev->device,
+                       "Couldn't send resources released packet(s)\n");
 
        memset(&pkt.teardown_packet, 0, sizeof(pkt.teardown_packet));
        init_completion(&comp_pkt.host_event);
@@ -2298,7 +2306,19 @@ static int hv_pci_remove(struct hv_device *hdev)
                               VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
        if (!ret)
                wait_for_completion_timeout(&comp_pkt.host_event, 10 * HZ);
+}
+
+/**
+ * hv_pci_remove() - Remove routine for this VMBus channel
+ * @hdev:      VMBus's tracking struct for this root PCI bus
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_pci_remove(struct hv_device *hdev)
+{
+       struct hv_pcibus_device *hbus;
 
+       hbus = hv_get_drvdata(hdev);
        if (hbus->state == hv_pcibus_installed) {
                /* Remove the bus from PCI's point of view. */
                pci_lock_rescan_remove();
@@ -2307,17 +2327,10 @@ static int hv_pci_remove(struct hv_device *hdev)
                pci_unlock_rescan_remove();
        }
 
-       ret = hv_send_resources_released(hdev);
-       if (ret)
-               dev_err(&hdev->device,
-                       "Couldn't send resources released packet(s)\n");
+       hv_pci_bus_exit(hdev);
 
        vmbus_close(hdev->channel);
 
-       /* Delete any children which might still exist. */
-       memset(&relations, 0, sizeof(relations));
-       hv_pci_devices_present(hbus, &relations);
-
        iounmap(hbus->cfg_addr);
        hv_free_config_window(hbus);
        pci_free_resource_list(&hbus->resources_for_children);