linux-kernel - Re: [PATCH v9] drm: Unplug drm device when unregistering it

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Date:   Thu, 13 Apr 2017 09:28:32 +0800
From:   jeffy <jeffy.chen@...k-chips.com>
To:     Sean Paul <seanpaul@...omium.org>
CC:     linux-kernel@...r.kernel.org, briannorris@...omium.org,
        dianders@...omium.org, tfiga@...omium.org, zyw@...k-chips.com,
        marcheu@...omium.org, mark.yao@...k-chips.com, hshi@...omium.org,
        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: Re: [PATCH v9] drm: Unplug drm device when unregistering it

Hi Sean,

On 04/12/2017 11:03 PM, Sean Paul wrote:
> On Wed, Apr 12, 2017 at 04:56:21PM +0800, Jeffy Chen wrote:
>> 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>
>>
>> Changes in v9:
>> Move drm_device_set_plug_state into drm_drv.c .
>>
>> Changes in v8:
>> Fix hang when unregistering drm dev with open_count 0.
>>
>> Changes in v7:
>> Add drm_device_set_plug_state helper.
>>
>> Changes in v6:
>> Reuse unplug status.
>>
>> Changes in v5:
>> Fix wrong git account.
>>
>> Changes in v2:
>> Fix some commit messages.
>>
>
> Hi Jeffy,
> A couple bookkeeping notes:
>
> - Please end the commit message with your Signed-off-by tag
> - No need to send cover letters for one patch. All info should be in the commit
>    message. Include superfluous information (such as tested on 4.4 kernel) after
>    ---
hmm...i'm using u-boot's patman tool to send patches. and the changelogs 
would be formated by the tool.

i'll switch changelogs to drm style.
>
>> ---
>>   drivers/gpu/drm/drm_drv.c     | 26 ++++++++++----------------
>>   drivers/gpu/drm/udl/udl_drv.c |  2 +-
>>   include/drm/drmP.h            |  6 ------
>>   include/drm/drm_drv.h         |  1 -
>>   4 files changed, 11 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
>> index b5c6bb4..e1da4d1 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
>> @@ -733,6 +717,13 @@ static void remove_compat_control_link(struct drm_device *dev)
>>   	kfree(name);
>>   }
>>
>> +static inline void drm_device_set_plug_state(struct drm_device *dev,
>> +					     bool plugged)
>> +{
>> +	smp_wmb();
>> +	atomic_set(&dev->unplugged, !plugged);
>> +}
>> +
>>   /**
>>    * drm_dev_register - Register DRM device
>>    * @dev: Device to register
>> @@ -787,6 +778,8 @@ 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 +819,7 @@ 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);
>
> I think you need drm_dev_unref here as well.
right, will do.
>
> Sean
>
>>   }
>>
>>   /*
>> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
>> index 3bfafcd..980a204 100644
>> --- a/include/drm/drmP.h
>> +++ b/include/drm/drmP.h
>> @@ -488,12 +488,6 @@ 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);
>> 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
>>
>