xen-pciback: reconfigure also from backend watch handler

When multiple PCI devices get assigned to a guest right at boot, libxl
incrementally populates the backend tree. The writes for the first of
the devices trigger the backend watch. In turn xen_pcibk_setup_backend()
will set the XenBus state to Initialised, at which point no further
reconfigures would happen unless a device got hotplugged. Arrange for
reconfigure to also get triggered from the backend watch handler.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: stable@vger.kernel.org
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/2337cbd6-94b9-4187-9862-c03ea12e0c61@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>

diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index 5188f02e75fb3202d27f9f57dd42cb5aa0232627..c09c7ebd6968d03cf115ccf7af9a4a8d477cd8a9 100644 (file)
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -359,7 +359,8 @@ out:
        return err;
 }
 
-static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
+static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev,
+                                enum xenbus_state state)
 {
        int err = 0;
        int num_devs;
@@ -373,9 +374,7 @@ static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
        dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
 
        mutex_lock(&pdev->dev_lock);
-       /* Make sure we only reconfigure once */
-       if (xenbus_read_driver_state(pdev->xdev->nodename) !=
-           XenbusStateReconfiguring)
+       if (xenbus_read_driver_state(pdev->xdev->nodename) != state)
                goto out;
 
        err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
@@ -500,6 +499,10 @@ static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
                }
        }
 
+       if (state != XenbusStateReconfiguring)
+               /* Make sure we only reconfigure once. */
+               goto out;
+
        err = xenbus_switch_state(pdev->xdev, XenbusStateReconfigured);
        if (err) {
                xenbus_dev_fatal(pdev->xdev, err,
@@ -525,7 +528,7 @@ static void xen_pcibk_frontend_changed(struct xenbus_device *xdev,
                break;
 
        case XenbusStateReconfiguring:
-               xen_pcibk_reconfigure(pdev);
+               xen_pcibk_reconfigure(pdev, XenbusStateReconfiguring);
                break;
 
        case XenbusStateConnected:
@@ -664,6 +667,15 @@ static void xen_pcibk_be_watch(struct xenbus_watch *watch,
                xen_pcibk_setup_backend(pdev);
                break;
 
+       case XenbusStateInitialised:
+               /*
+                * We typically move to Initialised when the first device was
+                * added. Hence subsequent devices getting added may need
+                * reconfiguring.
+                */
+               xen_pcibk_reconfigure(pdev, XenbusStateInitialised);
+               break;
+
        default:
                break;
        }