linux-kernel - [PATCH v6 1/2] drm: Unplug drm device when unregistering it

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Message-Id: <1491818445-11409-2-git-send-email-jeffy.chen@rock-chips.com>
Date:   Mon, 10 Apr 2017 18:00:44 +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>,
        Patrik Jakobsson <patrik.r.jakobsson@...il.com>,
        Dave Airlie <airlied@...hat.com>
Subject: [PATCH v6 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>
---

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     | 6 +++---
 drivers/gpu/drm/udl/udl_drv.c | 2 +-
 include/drm/drmP.h            | 6 ++++++
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index b5c6bb4..f38de26 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -357,9 +357,6 @@ 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);
@@ -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_plugged(dev);
+
 	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..c930a77 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -488,6 +488,12 @@ 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_plugged(struct drm_device *dev)
+{
+	smp_wmb();
+	atomic_set(&dev->unplugged, 0);
+}
+
 static inline void drm_device_set_unplugged(struct drm_device *dev)
 {
 	smp_wmb();
-- 
2.1.4