ACPI: video - remove unsafe uses of list_for_each_safe()

list_for_each_safe() only protects list from list alterations
performed by the same thread. One still needs to implement
proper locking when list is being accessed from several threads.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index be66a7c..36b64a7 100644 (file)
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -1462,12 +1462,14 @@ acpi_video_bus_get_one_device(struct acpi_device *device,
 
 static void acpi_video_device_rebind(struct acpi_video_bus *video)
 {
-       struct list_head *node, *next;
-       list_for_each_safe(node, next, &video->video_device_list) {
-               struct acpi_video_device *dev =
-                   container_of(node, struct acpi_video_device, entry);
+       struct acpi_video_device *dev;
+
+       down(&video->sem);
+
+       list_for_each_entry(dev, &video->video_device_list, entry)
                acpi_video_device_bind(video, dev);
-       }
+
+       up(&video->sem);
 }
 
 /*
@@ -1592,30 +1594,33 @@ static int acpi_video_device_enumerate(struct acpi_video_bus *video)
 
 static int acpi_video_switch_output(struct acpi_video_bus *video, int event)
 {
-       struct list_head *node, *next;
+       struct list_head *node;
        struct acpi_video_device *dev = NULL;
        struct acpi_video_device *dev_next = NULL;
        struct acpi_video_device *dev_prev = NULL;
        unsigned long state;
        int status = 0;
 
+       down(&video->sem);
 
-       list_for_each_safe(node, next, &video->video_device_list) {
+       list_for_each(node, &video->video_device_list) {
                dev = container_of(node, struct acpi_video_device, entry);
                status = acpi_video_device_get_state(dev, &state);
                if (state & 0x2) {
-                       dev_next =
-                           container_of(node->next, struct acpi_video_device,
-                                        entry);
-                       dev_prev =
-                           container_of(node->prev, struct acpi_video_device,
-                                        entry);
+                       dev_next = container_of(node->next,
+                                       struct acpi_video_device, entry);
+                       dev_prev = container_of(node->prev,
+                                       struct acpi_video_device, entry);
                        goto out;
                }
        }
+
        dev_next = container_of(node->next, struct acpi_video_device, entry);
        dev_prev = container_of(node->prev, struct acpi_video_device, entry);
-      out:
+
+ out:
+       up(&video->sem);
+
        switch (event) {
        case ACPI_VIDEO_NOTIFY_CYCLE:
        case ACPI_VIDEO_NOTIFY_NEXT_OUTPUT:
@@ -1691,24 +1696,17 @@ acpi_video_bus_get_devices(struct acpi_video_bus *video,
                           struct acpi_device *device)
 {
        int status = 0;
-       struct list_head *node, *next;
-
+       struct acpi_device *dev;
 
        acpi_video_device_enumerate(video);
 
-       list_for_each_safe(node, next, &device->children) {
-               struct acpi_device *dev =
-                   list_entry(node, struct acpi_device, node);
-
-               if (!dev)
-                       continue;
+       list_for_each_entry(dev, &device->children, node) {
 
                status = acpi_video_bus_get_one_device(dev, video);
                if (ACPI_FAILURE(status)) {
                        ACPI_EXCEPTION((AE_INFO, status, "Cant attach device"));
                        continue;
                }
-
        }
        return status;
 }
@@ -1724,9 +1722,6 @@ static int acpi_video_bus_put_one_device(struct acpi_video_device *device)
 
        video = device->video;
 
-       down(&video->sem);
-       list_del(&device->entry);
-       up(&video->sem);
        acpi_video_device_remove_fs(device->dev);
 
        status = acpi_remove_notify_handler(device->dev->handle,
@@ -1734,32 +1729,34 @@ static int acpi_video_bus_put_one_device(struct acpi_video_device *device)
                                            acpi_video_device_notify);
        backlight_device_unregister(device->backlight);
        video_output_unregister(device->output_dev);
+
        return 0;
 }
 
 static int acpi_video_bus_put_devices(struct acpi_video_bus *video)
 {
        int status;
-       struct list_head *node, *next;
+       struct acpi_video_device *dev, *next;
 
+       down(&video->sem);
 
-       list_for_each_safe(node, next, &video->video_device_list) {
-               struct acpi_video_device *data =
-                   list_entry(node, struct acpi_video_device, entry);
-               if (!data)
-                       continue;
+       list_for_each_entry_safe(dev, next, &video->video_device_list, entry) {
 
-               status = acpi_video_bus_put_one_device(data);
+               status = acpi_video_bus_put_one_device(dev);
                if (ACPI_FAILURE(status))
                        printk(KERN_WARNING PREFIX
                               "hhuuhhuu bug in acpi video driver.\n");
 
-               if (data->brightness)
-                       kfree(data->brightness->levels);
-               kfree(data->brightness);
-               kfree(data);
+               if (dev->brightness) {
+                       kfree(dev->brightness->levels);
+                       kfree(dev->brightness);
+               }
+               list_del(&dev->entry);
+               kfree(dev);
        }
 
+       up(&video->sem);
+
        return 0;
 }