[Xen-changelog] Added some DPRINTK statements, for debugging.

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User emellor@ewan
# Node ID 6fda96e7f3329b376f4e5f47483d126446f514ba
# Parent  d79ab87e27b8f88621234f7fb5bfeb24a8d33a89
# Parent  96cc6aa196b6e079488fabcc2eef32c38f7ff890
Added some DPRINTK statements, for debugging.

diff -r d79ab87e27b8 -r 6fda96e7f332 
linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c Mon Oct  3 15:40:27 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c Tue Oct  4 10:27:37 2005
@@ -63,13 +63,23 @@
        struct backend_info *be
                = container_of(watch, struct backend_info, watch);
 
+       DPRINTK("frontend_changed: %s.\n", be->frontpath);
+
        /* If other end is gone, delete ourself. */
        if (node && !xenbus_exists(be->frontpath, "")) {
+               DPRINTK("Frontend has disappeared; unregistering device.\n");
                device_unregister(&be->dev->dev);
                return;
        }
-       if (be->blkif == NULL || be->blkif->status == CONNECTED)
-               return;
+       if (be->blkif == NULL) {
+               DPRINTK("blkif is null; doing nothing.\n");
+               return;
+       }
+
+       if (be->blkif->status == CONNECTED) {
+               DPRINTK("blkif is CONNECTED; doing nothing.\n");
+               return;
+       }
 
        err = xenbus_gather(be->frontpath, "ring-ref", "%lu", &ring_ref,
                            "event-channel", "%u", &evtchn, NULL);
@@ -132,10 +142,11 @@
 
        xenbus_dev_ok(be->dev);
 
+       DPRINTK("frontend_changed(%s) finished OK.\n", be->frontpath);
        return;
-
  abort:
        xenbus_transaction_end(1);
+       DPRINTK("frontend_changed(%s) aborted.\n", be->frontpath);
 }
 
 /* 
@@ -152,9 +163,13 @@
                = container_of(watch, struct backend_info, backend_watch);
        struct xenbus_device *dev = be->dev;
 
+       DPRINTK("backend_changed: %s\n", watch->node);
+
        err = xenbus_scanf(dev->nodename, "physical-device", "%li", &pdev);
-       if (XENBUS_EXIST_ERR(err))
-               return;
+       if (XENBUS_EXIST_ERR(err)) {
+               DPRINTK("physical-device node exists; doing nothing.\n");
+               return;
+       }
        if (err < 0) {
                xenbus_dev_error(dev, err, "reading physical-device");
                return;
@@ -174,6 +189,8 @@
        }
 
        if (be->blkif == NULL) {
+               DPRINTK("be->blkif is null; creating VBD.\n");
+
                /* Front end dir is a number, which is used as the handle. */
                p = strrchr(be->frontpath, '/') + 1;
                handle = simple_strtoul(p, NULL, 0);
@@ -197,6 +214,11 @@
                /* Pass in NULL node to skip exist test. */
                frontend_changed(&be->watch, NULL);
        }
+       else {
+               DPRINTK("be->blkif is non-null; doing nothing.\n");
+       }
+
+       DPRINTK("backend_changed(%s) finished OK.\n", watch->node);
 }
 
 static int blkback_probe(struct xenbus_device *dev,
@@ -218,8 +240,10 @@
                            "frontend-id", "%li", &be->frontend_id,
                            "frontend", NULL, &frontend,
                            NULL);
-       if (XENBUS_EXIST_ERR(err))
-               goto free_be;
+       if (XENBUS_EXIST_ERR(err)) {
+               DPRINTK("blkback_probe: %s does not exist", dev->nodename);
+               goto free_be;
+       }
        if (err < 0) {
                xenbus_dev_error(dev, err,
                                 "reading %s/frontend or frontend-id",
@@ -231,6 +255,8 @@
                 * then our bus-id is no longer valid and we need to
                 * destroy the backend device.
                 */
+               DPRINTK("blkback_probe: failed to get frontend path and ID; "
+                       "destroying backend device");
                err = -ENOENT;
                goto free_be;
        }

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