linux-kernel - [PATCH v8 1/2] drm: Unplug drm device when unregistering it

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Message-Id: <1491965730-31393-2-git-send-email-jeffy.chen@rock-chips.com>
Date:   Wed, 12 Apr 2017 10:55:29 +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 v8 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.

Also drop drm_unplug_dev, because it would be unused after other changes.

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

---

Changes in v8:
Fix hang when unregistering drm dev with open_count 0

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     | 19 +++----------------
 drivers/gpu/drm/udl/udl_drv.c |  2 +-
 include/drm/drmP.h            |  5 +++--
 include/drm/drm_drv.h         |  1 -
 4 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index b5c6bb4..cc2d018 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
@@ -787,6 +771,8 @@ 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 +812,7 @@ 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..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)
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