On Mon, May 29, 2017 at 5:25 PM, Chris Wilson chris@chris-wilson.co.uk wrote:
convince us to look into this patch again? -Chris
drivers/gpu/drm/drm_drv.c | 26 ++++++++++---------------- drivers/gpu/drm/udl/udl_drv.c | 3 ++- include/drm/drmP.h | 6 ------ include/drm/drm_drv.h | 1 - 4 files changed, 12 insertions(+), 24 deletions(-)
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index b5c6bb4..e1da4d1 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -355,22 +355,6 @@ void drm_put_dev(struct drm_device *dev) } EXPORT_SYMBOL(drm_put_dev);
-void drm_unplug_dev(struct drm_device *dev) -{
- /* for a USB device */
- drm_dev_unregister(dev);
- mutex_lock(&drm_global_mutex);
- drm_device_set_unplugged(dev);
- if (dev->open_count == 0) {
drm_put_dev(dev);- }
- mutex_unlock(&drm_global_mutex);
-} -EXPORT_SYMBOL(drm_unplug_dev);
/*
- DRM internal mount
- We want to be able to allocate our own "struct address_space" to control
@@ -733,6 +717,13 @@ static void remove_compat_control_link(struct drm_device *dev) kfree(name); }
+static inline void drm_device_set_plug_state(struct drm_device *dev,
bool plugged)+{
- smp_wmb();
- atomic_set(&dev->unplugged, !plugged);
+}
/**
- drm_dev_register - Register DRM device
- @dev: Device to register
@@ -787,6 +778,8 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags) if (drm_core_check_feature(dev, DRIVER_MODESET)) drm_modeset_register_all(dev);
drm_device_set_plug_state(dev, true);
ret = 0;
DRM_INFO("Initialized %s %d.%d.%d %s for %s on minor %d\n",
@@ -826,6 +819,7 @@ void drm_dev_unregister(struct drm_device *dev) drm_lastclose(dev);
dev->registered = false;
drm_device_set_plug_state(dev, false);
if (drm_core_check_feature(dev, DRIVER_MODESET)) drm_modeset_unregister_all(dev);
diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c index cd8b017..fc73e24 100644 --- a/drivers/gpu/drm/udl/udl_drv.c +++ b/drivers/gpu/drm/udl/udl_drv.c @@ -108,7 +108,8 @@ static void udl_usb_disconnect(struct usb_interface *interface) drm_kms_helper_poll_disable(dev); udl_fbdev_unplug(dev); udl_drop_usb(dev);
- drm_unplug_dev(dev);
- drm_dev_unregister(dev);
- drm_dev_unref(dev);
}
/* diff --git a/include/drm/drmP.h b/include/drm/drmP.h index 3bfafcd..980a204 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -488,12 +488,6 @@ static __inline__ int drm_core_check_feature(struct drm_device *dev, return ((dev->driver->driver_features & feature) ? 1 : 0); }
-static inline void drm_device_set_unplugged(struct drm_device *dev) -{
- smp_wmb();
- atomic_set(&dev->unplugged, 1);
-}
static inline int drm_device_is_unplugged(struct drm_device *dev) { int ret = atomic_read(&dev->unplugged); diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h index 0fefc3f..eb63078 100644 --- a/include/drm/drm_drv.h +++ b/include/drm/drm_drv.h @@ -544,7 +544,6 @@ void drm_dev_unregister(struct drm_device *dev); void drm_dev_ref(struct drm_device *dev); void drm_dev_unref(struct drm_device *dev); void drm_put_dev(struct drm_device *dev); -void drm_unplug_dev(struct drm_device *dev);
int drm_dev_set_unique(struct drm_device *dev, const char *name);
I have no experience writing drivers. So, feel free to disregard my suggestion if it does not makes sense. I'm trying to update a driver for a USB device and Hans is helping me with it. I had some problems when plugging and unplugging the device and ended finding Jeffy's patch. I made the same changes to the driver I was working on and it behaved a bit better. When I told Hans about it, he found the problem with the calls in drm_release.
I'm not sure what is the best way to fix/improve the situation but, wouldn't it be a good idea to guard dangerous calls like unregister or unplug so that there are no side effects if they are called more times then they should? I mean, if a driver does so, it is already broken, but I think that keeping the kernel safe is a better choice, no?