[Xen-changelog] Fix driver to work with updated probe driver.

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

# HG changeset patch
# User cl349@xxxxxxxxxxxxxxxxxxxx
# Node ID 73b23942d6f5199d882e50205b0051ef50bc1cb0
# Parent  b399599f2ff83fe438c66f23bb1eb8490f55a0b1
Fix driver to work with updated probe driver.
Signed-off-by: Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>

diff -r b399599f2ff8 -r 73b23942d6f5 
linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c Fri Aug 19 12:13:31 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c Fri Aug 19 12:14:41 2005
@@ -44,11 +44,15 @@
 {
        struct backend_info *be = dev->data;
 
-       unregister_xenbus_watch(&be->watch);
+       if (be->watch.node)
+               unregister_xenbus_watch(&be->watch);
        unregister_xenbus_watch(&be->backend_watch);
-       vbd_free(be->blkif, be->vbd);
-       blkif_put(be->blkif);
-       kfree(be->frontpath);
+       if (be->vbd)
+               vbd_free(be->blkif, be->vbd);
+       if (be->blkif)
+               blkif_put(be->blkif);
+       if (be->frontpath)
+               kfree(be->frontpath);
        kfree(be);
        return 0;
 }
@@ -62,17 +66,14 @@
        struct backend_info *be
                = container_of(watch, struct backend_info, watch);
 
-       // printk("Got front end event on %s (%s)\n", node, be->frontpath);
-
-       if (vbd_is_active(be->vbd)) {
-               /* If other end is gone, delete ourself. */
-               if (!xenbus_exists(be->frontpath, "")) {
-                       // printk("Removing...\n");
-                       xenbus_rm(be->dev->nodename, "");
-                       device_unregister(&be->dev->dev);
-               }
-               return;
-       }
+       /* If other end is gone, delete ourself. */
+       if (!xenbus_exists(be->frontpath, "")) {
+               xenbus_rm(be->dev->nodename, "");
+               device_unregister(&be->dev->dev);
+               return;
+       }
+       if (vbd_is_active(be->vbd))
+               return;
 
 #ifndef CONFIG_XEN_BLKDEV_GRANT
        err = xenbus_gather(be->frontpath, "shared-frame", "%lu", &sharedmfn,
@@ -176,42 +177,20 @@
                = container_of(watch, struct backend_info, backend_watch);
        struct xenbus_device *dev = be->dev;
 
-       err = xenbus_scanf(dev->nodename, "frontend-id", "%li",
-                          &be->frontend_id);
-       if (err == -ENOENT || err == -ERANGE)
-               goto out;
-       if (err < 0) {
-               xenbus_dev_error(dev, err, "Reading frontend-id");
-               goto out;
-       }
-
-       err = xenbus_scanf(dev->nodename, "physical-device", "%li", &pdev);
-       if (err == -ENOENT || err == -ERANGE)
-               goto out;
-       if (err < 0) {
-               xenbus_dev_error(dev, err, "Reading physical-device");
-               goto out;
-       }
-       if (be->pdev && be->pdev != pdev) {
-               printk(KERN_WARNING
-                      "changing physical-device not supported\n");
-               return;
-       }
-       be->pdev = pdev;
-
-       frontend = xenbus_read(dev->nodename, "frontend", NULL);
-       if (IS_ERR(frontend))
-               return;
-       if (strlen(frontend) == 0) {
-               kfree(frontend);
-               return;
-       }
-
-       /* If there's a read-only node, we're read only. */
-       p = xenbus_read(dev->nodename, "read-only", NULL);
-       if (!IS_ERR(p)) {
-               be->readonly = 1;
-               kfree(p);
+       frontend = NULL;
+       err = xenbus_gather(dev->nodename,
+                           "frontend-id", "%li", &be->frontend_id,
+                           "frontend", NULL, &frontend,
+                           NULL);
+       if (err == -ENOENT || err == -ERANGE ||
+           strlen(frontend) == 0 || !xenbus_exists(frontend, "")) {
+               if (frontend)
+                       kfree(frontend);
+               /* If we can't get a frontend path and a frontend-id,
+                * then our bus-id is no longer valid and we need to
+                * destroy the backend device.
+                */
+               goto device_fail;
        }
 
        if (!be->frontpath || strcmp(frontend, be->frontpath)) {
@@ -223,9 +202,35 @@
                be->watch.node = be->frontpath;
                be->watch.callback = frontend_changed;
                err = register_xenbus_watch(&be->watch);
-               if (err)
-                       goto out;
-
+               if (err) {
+                       be->watch.node = NULL;
+                       goto device_fail;
+               }
+       } else
+               kfree(frontend);
+
+       err = xenbus_scanf(dev->nodename, "physical-device", "%li", &pdev);
+       if (err == -ENOENT || err == -ERANGE)
+               goto out;
+       if (err < 0) {
+               xenbus_dev_error(dev, err, "Reading physical-device");
+               goto device_fail;
+       }
+       if (be->pdev && be->pdev != pdev) {
+               printk(KERN_WARNING
+                      "changing physical-device not supported\n");
+               goto device_fail;
+       }
+       be->pdev = pdev;
+
+       /* If there's a read-only node, we're read only. */
+       p = xenbus_read(dev->nodename, "read-only", NULL);
+       if (!IS_ERR(p)) {
+               be->readonly = 1;
+               kfree(p);
+       }
+
+       if (be->blkif == NULL) {
                /* Front end dir is a number, which is used as the handle. */
                p = strrchr(be->frontpath, '/') + 1;
                handle = simple_strtoul(p, NULL, 0);
@@ -234,30 +239,24 @@
                if (IS_ERR(be->blkif)) {
                        err = PTR_ERR(be->blkif);
                        be->blkif = NULL;
-                       goto free_watch;
+                       goto device_fail;
                }
 
                be->vbd = vbd_create(be->blkif, handle, be->pdev,
                                     be->readonly);
                if (IS_ERR(be->vbd)) {
                        err = PTR_ERR(be->vbd);
-                       blkif_put(be->blkif);
-                       be->blkif = NULL;
                        be->vbd = NULL;
-                       goto free_watch;
+                       goto device_fail;
                }
 
                frontend_changed(&be->watch, be->frontpath);
-       } else
-               kfree(frontend);
+       }
 
        return;
 
- free_watch:
-       unregister_xenbus_watch(&be->watch);
-       be->watch.node = NULL;
-       kfree(be->frontpath);
-       be->frontpath = NULL;
+ device_fail:
+       device_unregister(&be->dev->dev);
  out:
        return;
 }
@@ -296,7 +295,7 @@
 };
 
 static struct xenbus_driver blkback = {
-       .name = __stringify(KBUILD_MODNAME),
+       .name = "vbd",
        .owner = THIS_MODULE,
        .ids = blkback_ids,
        .probe = blkback_probe,

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