linux-kernel - [PATCH v7 1/2] drm: Unplug drm device when unregistering it

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Message-Id: <1491881502-24357-2-git-send-email-jeffy.chen@rock-chips.com>
Date:   Tue, 11 Apr 2017 11:31:41 +0800
From:   Jeffy Chen <jeffy.chen@...k-chips.com>
To:     linux-kernel@...r.kernel.org
Cc:     briannorris@...omium.org, dianders@...omium.org,
        tfiga@...omium.org, seanpaul@...omium.org, zyw@...k-chips.com,
        marcheu@...omium.org, mark.yao@...k-chips.com, hshi@...omium.org,
        Jeffy Chen <jeffy.chen@...k-chips.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        dri-devel@...ts.freedesktop.org,
        Chris Wilson <chris@...is-wilson.co.uk>,
        David Airlie <airlied@...ux.ie>, Tom Gundersen <teg@...m.no>,
        Dave Airlie <airlied@...hat.com>
Subject: [PATCH v7 1/2] drm: Unplug drm device when unregistering it

After unbinding drm, the user space may still owns the drm dev fd,
and may still be able to call drm ioctl.

We're using an unplugged state to prevent something like that, so
let's reuse it here.

Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
Reviewed-by: Sean Paul <seanpaul@...omium.org>

---

Changes in v7:
Address Sean Paul <seanpaul@...omium.org>'s comments.

Changes in v6:
Address Daniel Vetter <daniel@...ll.ch>'s comments.

Changes in v5:
Fix wrong git account.

Changes in v2:
Fix some commit messages.

 drivers/gpu/drm/drm_drv.c     | 8 ++++----
 drivers/gpu/drm/udl/udl_drv.c | 2 +-
 include/drm/drmP.h            | 5 +++--
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index b5c6bb4..ad13e20 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -357,12 +357,9 @@ 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);
+	drm_device_set_plug_state(dev, false);
 
 	if (dev->open_count == 0) {
 		drm_put_dev(dev);
@@ -787,6 +784,8 @@ 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 +825,7 @@ void drm_dev_unregister(struct drm_device *dev)
 	drm_lastclose(dev);
 
 	dev->registered = false;
+	drm_unplug_dev(dev);
 
 	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..5dbd916 100644
--- a/drivers/gpu/drm/udl/udl_drv.c
+++ b/drivers/gpu/drm/udl/udl_drv.c
@@ -108,7 +108,7 @@ 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);
 }
 
 /*
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 3bfafcd..a9a5a64 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -488,10 +488,11 @@ 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)
+static inline void drm_device_set_plug_state(struct drm_device *dev,
+					     bool plugged)
 {
 	smp_wmb();
-	atomic_set(&dev->unplugged, 1);
+	atomic_set(&dev->unplugged, !plugged);
 }
 
 static inline int drm_device_is_unplugged(struct drm_device *dev)
-- 
2.1.4