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Subject[PATCH] drm: Fixup hang when unregistering drm dev with open_count 0
Date
My previous patch (c5d8fac2bf  drm: Unplug drm device when unregistering
it) calls drm_unplug_dev when unregistering drm dev. But if open_count
is 0, the unplug will try to unregister the drm dev again and cause
deadlock.

Fix it by dropping drm_unplug_dev and use drm_device_set_plug_state
directly.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>

---

drivers/gpu/drm/drm_drv.c | 15 +--------------
include/drm/drm_drv.h | 1 -
2 files changed, 1 insertion(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index ad13e20..cc2d018 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -355,19 +355,6 @@ void drm_put_dev(struct drm_device *dev)
}
EXPORT_SYMBOL(drm_put_dev);

-void drm_unplug_dev(struct drm_device *dev)
-{
- mutex_lock(&drm_global_mutex);
-
- drm_device_set_plug_state(dev, false);
-
- 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
@@ -825,7 +812,7 @@ void drm_dev_unregister(struct drm_device *dev)
drm_lastclose(dev);

dev->registered = false;
- drm_unplug_dev(dev);
+ drm_device_set_plug_state(dev, false);

if (drm_core_check_feature(dev, DRIVER_MODESET))
drm_modeset_unregister_all(dev);
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);

--
2.1.4

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