[Xen-changelog] Fix locking: probe can be called from several places, so ensure

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

# HG changeset patch
# User cl349@xxxxxxxxxxxxxxxxxxxx
# Node ID b5219630030688d67a6454c21d9a3aa400009ef1
# Parent  c1c2a023dbc49bec7d6bdbd65514f91649b7e422
Fix locking: probe can be called from several places, so ensure
we lock for it.
Signed-off-by: Rusty Russel <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>

diff -r c1c2a023dbc4 -r b52196300306 
linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
--- a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c    Tue Jul 26 
17:19:38 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c    Tue Jul 26 
17:22:38 2005
@@ -47,10 +47,13 @@
                if (!streq(arr->devicetype, dev->devicetype))
                        continue;
 
-               if (streq(arr->subtype, "") ||
-                   streq(arr->subtype, dev->subtype)) {
+               /* If they don't care what subtype, it's a match. */
+               if (streq(arr->subtype, ""))
                        return arr;
-               }
+
+               /* If they care, device must have (same) subtype. */
+               if (dev->subtype && streq(arr->subtype, dev->subtype))
+                       return arr;
        }
        return NULL;
 }
@@ -99,18 +102,25 @@
 
 int xenbus_register_driver(struct xenbus_driver *drv)
 {
+       int err;
+
        drv->driver.name = drv->name;
        drv->driver.bus = &xenbus_type;
        drv->driver.owner = drv->owner;
        drv->driver.probe = xenbus_dev_probe;
        drv->driver.remove = xenbus_dev_remove;
 
-       return driver_register(&drv->driver);
+       down(&xenbus_lock);
+       err = driver_register(&drv->driver);
+       up(&xenbus_lock);
+       return err;
 }
 
 void xenbus_unregister_driver(struct xenbus_driver *drv)
 {
+       down(&xenbus_lock);
        driver_unregister(&drv->driver);
+       up(&xenbus_lock);
 }
 
 struct xb_find_info
@@ -203,20 +213,16 @@
        char **dir;
        unsigned int i, dir_n;
 
-       down(&xenbus_lock);
        dir = xenbus_directory(path, "", &dir_n);
-       if (IS_ERR(dir)) {
-               err = PTR_ERR(dir);
-               goto unlock;
-       }
+       if (IS_ERR(dir))
+               return PTR_ERR(dir);
+
        for (i = 0; i < dir_n; i++) {
                err = xenbus_probe_device_type(path, dir[i]);
                if (err)
                        break;
        }
        kfree(dir);
-unlock:
-       up(&xenbus_lock);
        return err;
 }
 
@@ -292,10 +298,10 @@
                return err;
        }
 
+       down(&xenbus_lock);
        /* Enumerate devices in xenstore. */
        xenbus_probe_devices("device");
-
-       down(&xenbus_lock);
+       /* Watch for changes. */
        register_xenbus_watch(&dev_watch);
        up(&xenbus_lock);
        return 0;

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