Also note that it is not currently feasible for UDL code to access drm_global_mutex.
Please also refer to the similar comments ("FIXME: open_count is protected by drm_global_mutex but that would lead to locking inversion with the driver load path.") in nouveau, i915 and amdgpu.
On Wed, Feb 10, 2016 at 12:51 PM, Haixia Shi <hshi@xxxxxxxxxxxx> wrote:
> This should rather be:
>
> drm_release(inode, filp);
> mutex_lock(&drm_global_mutex);
> if (!dev->open_count && udl_device_is_unplugged(dev))
> drm_put_dev(dev);
> mutex_unlock(&drm_global_mutex);
>
> return 0;
>
> There is no reason to look at the return code of drm_release(), ever.But drm_release() does return a retcode. It would still make sense to return that as-is in case any existing code relies on it.On Wed, Feb 10, 2016 at 4:24 AM, David Herrmann <dh.herrmann@xxxxxxxxx> wrote:Hi
This doesn't make sense to me. You're called here with global-mutex
On Tue, Feb 9, 2016 at 10:05 PM, Haixia Shi <hshi@xxxxxxxxxxxx> wrote:
> 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.
>
> Signed-off-by: Haixia Shi <hshi@xxxxxxxxxxxx>
> Reviewed-by: Stéphane Marchesin <marcheu@xxxxxxxxxxxx>
> ---
> 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_drv.c | 7 +++--
> drivers/gpu/drm/udl/udl_drv.h | 6 ++++
> drivers/gpu/drm/udl/udl_fb.c | 2 +-
> drivers/gpu/drm/udl/udl_gem.c | 5 +++
> drivers/gpu/drm/udl/udl_main.c | 61 +++++++++++++++++++++++++++++++++++++
> include/drm/drmP.h | 14 ---------
> 12 files changed, 78 insertions(+), 36 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..b168f2c 100644
> --- a/drivers/gpu/drm/udl/udl_connector.c
> +++ b/drivers/gpu/drm/udl/udl_connector.c
> @@ -96,7 +96,7 @@ 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))
> + if (udl_device_is_unplugged(connector->dev))
> return connector_status_disconnected;
> return connector_status_connected;
> }
> diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c
> index d5728ec..f5c2a97 100644
> --- a/drivers/gpu/drm/udl/udl_drv.c
> +++ b/drivers/gpu/drm/udl/udl_drv.c
> @@ -24,12 +24,12 @@ static const struct vm_operations_struct udl_gem_vm_ops = {
>
> static const struct file_operations udl_driver_fops = {
> .owner = THIS_MODULE,
> - .open = drm_open,
> + .open = udl_drm_open,
> .mmap = udl_drm_gem_mmap,
> .poll = drm_poll,
> .read = drm_read,
> - .unlocked_ioctl = drm_ioctl,
> - .release = drm_release,
> + .unlocked_ioctl = udl_drm_ioctl,
> + .release = udl_drm_release,
> #ifdef CONFIG_COMPAT
> .compat_ioctl = drm_compat_ioctl,
> #endif
> @@ -97,6 +97,7 @@ static void udl_usb_disconnect(struct usb_interface *interface)
> drm_connector_unplug_all(dev);
> udl_fbdev_unplug(dev);
> udl_drop_usb(dev);
> + udl_device_set_unplugged(dev);
> drm_unplug_dev(dev);
> }
>
> diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h
> index 4a064ef..75aa91c 100644
> --- a/drivers/gpu/drm/udl/udl_drv.h
> +++ b/drivers/gpu/drm/udl/udl_drv.h
> @@ -65,6 +65,7 @@ struct udl_device {
> atomic_t bytes_identical; /* saved effort with backbuffer comparison */
> atomic_t bytes_sent; /* to usb, after compression including overhead */
> atomic_t cpu_kcycles_used; /* transpired during pixel processing */
> + atomic_t unplugged; /* device has been unplugged or gone away */
> };
>
> struct udl_gem_object {
> @@ -133,6 +134,9 @@ int udl_gem_get_pages(struct udl_gem_object *obj);
> void udl_gem_put_pages(struct udl_gem_object *obj);
> int udl_gem_vmap(struct udl_gem_object *obj);
> void udl_gem_vunmap(struct udl_gem_object *obj);
> +int udl_drm_open(struct inode *inode, struct file *filp);
> +int udl_drm_release(struct inode *inode, struct file *filp);
> +int udl_drm_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
> int udl_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
> int udl_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf);
>
> @@ -140,6 +144,8 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
> int width, int height);
>
> int udl_drop_usb(struct drm_device *dev);
> +void udl_device_set_unplugged(struct drm_device *dev);
> +int udl_device_is_unplugged(struct drm_device *dev);
>
> #define CMD_WRITE_RAW8 "\xAF\x60" /**< 8 bit raw write command. */
> #define CMD_WRITE_RL8 "\xAF\x61" /**< 8 bit run length command. */
> diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
> index 200419d..df1d53e 100644
> --- a/drivers/gpu/drm/udl/udl_fb.c
> +++ b/drivers/gpu/drm/udl/udl_fb.c
> @@ -325,7 +325,7 @@ static int udl_fb_open(struct fb_info *info, int user)
> 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))
> + if (udl_device_is_unplugged(udl->ddev))
> return -ENODEV;
>
> ufbdev->fb_count++;
> diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c
> index 2a0a784..33c302f 100644
> --- a/drivers/gpu/drm/udl/udl_gem.c
> +++ b/drivers/gpu/drm/udl/udl_gem.c
> @@ -86,8 +86,13 @@ int udl_dumb_create(struct drm_file *file,
>
> int udl_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
> {
> + struct drm_file *priv = filp->private_data;
> + struct drm_device *dev = priv->minor->dev;
> int ret;
>
> + if (udl_device_is_unplugged(dev))
> + return -ENODEV;
> +
> ret = drm_gem_mmap(filp, vma);
> if (ret)
> return ret;
> diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c
> index 33dbfb2..2ba3ee3 100644
> --- a/drivers/gpu/drm/udl/udl_main.c
> +++ b/drivers/gpu/drm/udl/udl_main.c
> @@ -350,3 +350,64 @@ int udl_driver_unload(struct drm_device *dev)
> kfree(udl);
> return 0;
> }
> +
> +int udl_drm_open(struct inode *inode, struct file *filp)
> +{
> + struct drm_file *file_priv;
> + struct drm_minor *minor;
> +
> + int ret = drm_open(inode, filp);
> + if (ret)
> + return ret;
> +
> + file_priv = filp->private_data;
> + minor = file_priv->minor;
> + if (udl_device_is_unplugged(minor->dev)) {
> + drm_dev_unref(minor->dev);
> + return -ENODEV;
> + }
held, so you can just check udl_device_is_unplugged() before calling
into drm_open().
> +
> + return 0;
> +}
> +
> +int udl_drm_release(struct inode *inode, struct file *filp)
> +{
> + struct drm_file *file_priv = filp->private_data;
> + struct drm_device *dev = file_priv->minor->dev;
> +
> + int ret = drm_release(inode, filp);
> + if (!dev->open_count && udl_device_is_unplugged(dev))
> + drm_put_dev(dev);
This should rather be:
drm_release(inode, filp);
mutex_lock(&drm_global_mutex);
if (!dev->open_count && udl_device_is_unplugged(dev))
drm_put_dev(dev);
mutex_unlock(&drm_global_mutex);
return 0;
There is no reason to look at the return code of drm_release(), ever.
> +
> + return ret;
> +}
> +
> +int udl_drm_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> +{
> + struct drm_file *file_priv = filp->private_data;
> + struct drm_device *dev = file_priv->minor->dev;
> + unsigned int nr = DRM_IOCTL_NR(cmd);
> +
> + if (udl_device_is_unplugged(dev) &&
> + nr != DRM_IOCTL_NR(DRM_IOCTL_MODE_SETCRTC) &&
> + nr != DRM_IOCTL_NR(DRM_IOCTL_MODE_RMFB) &&
> + nr != DRM_IOCTL_NR(DRM_IOCTL_MODE_DESTROY_DUMB))
> + return -ENODEV;
Why?
Just do:
if (udl_device_is_unplugged(dev))
return -ENODEV;
Why this complex logic here?
Thanks
David
> +
> + return drm_ioctl(filp, cmd, arg);
> +}
> +
> +void udl_device_set_unplugged(struct drm_device *dev)
> +{
> + struct udl_device *udl = dev->dev_private;
> + smp_wmb();
> + atomic_set(&udl->unplugged, 1);
> +}
> +
> +int udl_device_is_unplugged(struct drm_device *dev)
> +{
> + struct udl_device *udl = dev->dev_private;
> + int ret = atomic_read(&udl->unplugged);
> + smp_rmb();
> + return ret;
> +}
> 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
>
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