David - is the v3 patch acceptable to you? Thanks.

On Fri, Feb 12, 2016 at 11:50 AM, Haixia Shi <hshi@chromium.org> wrote:
v1: Remove the general drm_device_is_unplugged() checks, and move the unplugged
flag handling logic into drm/udl. In general we want to keep driver-specific
logic out of common drm code.

v2: Based on discussion with Stephane and David, drop most of the unplugged
flag handling logic in drm/udl except for udl_detect() and udl_fb_open().
The intention is to treat the device removal as a connector-unplug, and kep
the UDL device fully functional.

v3: Based on feedback from David, entirely drop the "unplugged" flag and all
related code. There is no need to check for the unplugged flag as the existing
udl_usb_disconnect() behavior already ensures the controller is removed, and
all code paths that uses the usb-device are not reachable after unplug.

When a UDL monitor is unplugged, we need to still treat it as a fully
functional device which just happens to have its connector unplugged.
This allows user-space to properly deallocate fbs and dumb buffers
before closing the device.

This drops the "unplugged" flag hack, which puts the device in a
non-functional state after USB unplug and rejects most operations on
the device such as ioctls with error -ENODEV.

Signed-off-by: Haixia Shi <hshi@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
---
 drivers/gpu/drm/drm_drv.c           |  6 ------
 drivers/gpu/drm/drm_fops.c          |  2 --
 drivers/gpu/drm/drm_gem.c           |  3 ---
 drivers/gpu/drm/drm_ioctl.c         |  3 ---
 drivers/gpu/drm/drm_vm.c            |  3 ---
 drivers/gpu/drm/udl/udl_connector.c |  2 --
 drivers/gpu/drm/udl/udl_fb.c        |  6 ------
 include/drm/drmP.h                  | 14 --------------
 8 files changed, 39 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 167c8d3..f93ee12 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -376,9 +376,6 @@ struct drm_minor *drm_minor_acquire(unsigned int minor_id)

        if (!minor) {
                return ERR_PTR(-ENODEV);
-       } else if (drm_device_is_unplugged(minor->dev)) {
-               drm_dev_unref(minor->dev);
-               return ERR_PTR(-ENODEV);
        }

        return minor;
@@ -464,9 +461,6 @@ void drm_unplug_dev(struct drm_device *dev)
        drm_minor_unregister(dev, DRM_MINOR_CONTROL);

        mutex_lock(&drm_global_mutex);
-
-       drm_device_set_unplugged(dev);
-
        if (dev->open_count == 0) {
                drm_put_dev(dev);
        }
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 1ea8790..b4332d4 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -497,8 +497,6 @@ int drm_release(struct inode *inode, struct file *filp)

        if (!--dev->open_count) {
                retcode = drm_lastclose(dev);
-               if (drm_device_is_unplugged(dev))
-                       drm_put_dev(dev);
        }
        mutex_unlock(&drm_global_mutex);

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 2e8c77e..c622e32 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -900,9 +900,6 @@ int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
        struct drm_vma_offset_node *node;
        int ret;

-       if (drm_device_is_unplugged(dev))
-               return -ENODEV;
-
        drm_vma_offset_lock_lookup(dev->vma_offset_manager);
        node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
                                                  vma->vm_pgoff,
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 8ce2a0c..f959074 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -695,9 +695,6 @@ long drm_ioctl(struct file *filp,

        dev = file_priv->minor->dev;

-       if (drm_device_is_unplugged(dev))
-               return -ENODEV;
-
        is_driver_ioctl = nr >= DRM_COMMAND_BASE && nr < DRM_COMMAND_END;

        if (is_driver_ioctl) {
diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
index f90bd5f..3a68be4 100644
--- a/drivers/gpu/drm/drm_vm.c
+++ b/drivers/gpu/drm/drm_vm.c
@@ -657,9 +657,6 @@ int drm_legacy_mmap(struct file *filp, struct vm_area_struct *vma)
        struct drm_device *dev = priv->minor->dev;
        int ret;

-       if (drm_device_is_unplugged(dev))
-               return -ENODEV;
-
        mutex_lock(&dev->struct_mutex);
        ret = drm_mmap_locked(filp, vma);
        mutex_unlock(&dev->struct_mutex);
diff --git a/drivers/gpu/drm/udl/udl_connector.c b/drivers/gpu/drm/udl/udl_connector.c
index 4709b54..a6d5e21 100644
--- a/drivers/gpu/drm/udl/udl_connector.c
+++ b/drivers/gpu/drm/udl/udl_connector.c
@@ -96,8 +96,6 @@ static int udl_mode_valid(struct drm_connector *connector,
 static enum drm_connector_status
 udl_detect(struct drm_connector *connector, bool force)
 {
-       if (drm_device_is_unplugged(connector->dev))
-               return connector_status_disconnected;
        return connector_status_connected;
 }

diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
index 200419d..29aca6c 100644
--- a/drivers/gpu/drm/udl/udl_fb.c
+++ b/drivers/gpu/drm/udl/udl_fb.c
@@ -321,12 +321,6 @@ static void udl_fb_imageblit(struct fb_info *info, const struct fb_image *image)
 static int udl_fb_open(struct fb_info *info, int user)
 {
        struct udl_fbdev *ufbdev = info->par;
-       struct drm_device *dev = ufbdev->ufb.base.dev;
-       struct udl_device *udl = dev->dev_private;
-
-       /* If the USB device is gone, we don't accept new opens */
-       if (drm_device_is_unplugged(udl->ddev))
-               return -ENODEV;

        ufbdev->fb_count++;

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index d7162cf..40c6099 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -748,7 +748,6 @@ struct drm_device {
        struct drm_minor *control;              /**< Control node */
        struct drm_minor *primary;              /**< Primary node */
        struct drm_minor *render;               /**< Render node */
-       atomic_t unplugged;                     /**< Flag whether dev is dead */
        struct inode *anon_inode;               /**< inode for private address-space */
        char *unique;                           /**< unique name of the device */
        /*@} */
@@ -879,19 +878,6 @@ 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);
-       smp_rmb();
-       return ret;
-}
-
 static inline bool drm_is_render_client(const struct drm_file *file_priv)
 {
        return file_priv->minor->type == DRM_MINOR_RENDER;
--
2.7.0.rc3.207.g0ac5344