[Devel] [PATCH RHEL7 COMMIT] ve/drivers: Do not forget to release mismatched device found

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-123.1.2-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-123.1.2.vz7.5.25
------>
commit 0dc34121a882509daf2207f8e0c3d4aa9d91914c
Author: Cyrill Gorcunov <gorcunov at virtuozzo.com>
Date:   Fri Jul 17 23:58:39 2015 +0400

    ve/drivers: Do not forget to release mismatched device found
    
    Upon call of device_destroy_namespace we walk over namespace devices
    looking for one which match on both device maj/min and VE itself,
    but the thing is that if device belong to another VE we continue
    iteration with never released get_device call.
    
    Thus rework device_destroy_namespace (thanks to vdavydov@
    for idea) -- pass __match_devt_ns matcher which would
    test for namespace inside class_find_device itself.
    
    https://jira.sw.ru/browse/PSBM-34777
    
    Signed-off-by: Cyrill Gorcunov <gorcunov at virtuozzo.com>
    Reviewed-by: Vladimir Davydov <vdavydov at parallels.com>
    
    CC: Andrey Vagin <avagin at virtuozzo.com>
    CC: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 drivers/base/core.c | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 6583bec..6167957 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1836,19 +1836,29 @@ void device_destroy(struct class *class, dev_t devt)
 }
 EXPORT_SYMBOL_GPL(device_destroy);
 
-void device_destroy_namespace(struct class *class, dev_t devt, void *ns)
+struct __match_devt_ns_arg {
+	dev_t	devt;
+	void	*ns;
+};
+
+static int __match_devt_ns(struct device *dev, const void *data)
 {
-	struct device *dev = NULL;
+	const struct __match_devt_ns_arg *arg = data;
 
-	for (;;) {
-		dev = class_find_device(class, dev, &devt, __match_devt);
-		if (!dev)
-			break;
-		if (!class->namespace ||
-		    (class->namespace(dev) == ns))
-			break;
-	}
+	return dev->devt == arg->devt &&
+		(!dev->class->namespace ||
+		 dev->class->namespace(dev) == arg->ns);
+}
+
+void device_destroy_namespace(struct class *class, dev_t devt, void *ns)
+{
+	struct __match_devt_ns_arg arg = {
+		.devt	= devt,
+		.ns	= ns,
+	};
+	struct device *dev;
 
+	dev = class_find_device(class, NULL, &arg, __match_devt_ns);
 	if (dev) {
 		put_device(dev);
 		device_unregister(dev);