[PATCH 1/3] drm/ttm: Provide struct ttm_global for referencing TTM global state
Koenig, Christian
Christian.Koenig at amd.com
Fri Oct 19 07:51:53 UTC 2018
Am 19.10.18 um 09:49 schrieb Daniel Vetter:
> On Fri, Oct 19, 2018 at 9:38 AM Thomas Zimmermann <tzimmermann at suse.de> wrote:
>> Hi,
>>
>> thanks for the review.
>>
>> Am 19.10.18 um 05:30 schrieb Huang Rui:
>>> On Fri, Oct 19, 2018 at 12:27:50AM +0800, Thomas Zimmermann wrote:
>>>> +int ttm_global_init(struct ttm_global *glob)
>>>> +{
>>>> + int ret;
>>>> +
>>> We would better add a protection here to make sure the glob is not NULL.
>>>
>>> if (!glob)
>>> return -EINVAL;
>> Passing a NULL pointer is a programming error, not a runtime error. I'd
>> rather use BUG_ON() for this test. Ok?
> if (WARN_ON(!glob)
> return -EINVAL;
>
> instead of BUG_ON is much friendly for debugging. Especially in gfx
> drivers, where the entire init runs while holding a few critical
> kernel locks (console_lock, among others), and so will result in a
> very silent death of the entire machine.
Yeah, additional to that a BUG_ON a NULL pointer is rather pointless.
Dereferencing the NULL pointer has pretty much the same effect as a
BUG_ON :)
Christian.
> -Daniel
>
>> Best regards
>> Thomas
>>
>>> Others, look good for me.
>>>
>>> Thanks,
>>> Ray
>>>
>>>> + glob->mem_ref.global_type = DRM_GLOBAL_TTM_MEM;
>>>> + glob->mem_ref.size = sizeof(struct ttm_mem_global);
>>>> + glob->bo_ref.object = NULL;
>>>> + glob->mem_ref.init = &ttm_global_init_mem;
>>>> + glob->mem_ref.release = &ttm_global_release_mem;
>>>> + ret = drm_global_item_ref(&glob->mem_ref);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + glob->bo_ref.global_type = DRM_GLOBAL_TTM_BO;
>>>> + glob->bo_ref.size = sizeof(struct ttm_bo_global);
>>>> + glob->bo_ref.object = NULL;
>>>> + glob->bo_ref.init = &ttm_global_init_bo;
>>>> + glob->bo_ref.release = &ttm_global_release_bo;
>>>> + ret = drm_global_item_ref(&glob->bo_ref);
>>>> + if (ret)
>>>> + goto err_drm_global_item_unref_mem;
>>>> +
>>>> + return 0;
>>>> +
>>>> +err_drm_global_item_unref_mem:
>>>> + drm_global_item_unref(&glob->mem_ref);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +EXPORT_SYMBOL(ttm_global_init);
>>>> +
>>>> +void ttm_global_release(struct ttm_global *glob)
>>>> +{
>>>> + drm_global_item_unref(&glob->bo_ref);
>>>> + drm_global_item_unref(&glob->mem_ref);
>>>> +}
>>>> +
>>>> +EXPORT_SYMBOL(ttm_global_release);
>>>> diff --git a/include/drm/drm_global.h b/include/drm/drm_global.h
>>>> index 3a830602a2e4..4482a9bbd6e9 100644
>>>> --- a/include/drm/drm_global.h
>>>> +++ b/include/drm/drm_global.h
>>>> @@ -28,8 +28,16 @@
>>>> * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
>>>> */
>>>>
>>>> +/*
>>>> + * The interfaces in this file are deprecated. Please use ttm_global
>>>> + * from <drm/ttm/ttm_global.h> instead.
>>>> + */
>>>> +
>>>> #ifndef _DRM_GLOBAL_H_
>>>> #define _DRM_GLOBAL_H_
>>>> +
>>>> +#include <linux/types.h>
>>>> +
>>>> enum drm_global_types {
>>>> DRM_GLOBAL_TTM_MEM = 0,
>>>> DRM_GLOBAL_TTM_BO,
>>>> diff --git a/include/drm/ttm/ttm_global.h b/include/drm/ttm/ttm_global.h
>>>> new file mode 100644
>>>> index 000000000000..06e791499f87
>>>> --- /dev/null
>>>> +++ b/include/drm/ttm/ttm_global.h
>>>> @@ -0,0 +1,79 @@
>>>> +/**************************************************************************
>>>> + *
>>>> + * Copyright 2008-2009 VMware, Inc., Palo Alto, CA., USA
>>>> + * All Rights Reserved.
>>>> + *
>>>> + * Permission is hereby granted, free of charge, to any person obtaining a
>>>> + * copy of this software and associated documentation files (the
>>>> + * "Software"), to deal in the Software without restriction, including
>>>> + * without limitation the rights to use, copy, modify, merge, publish,
>>>> + * distribute, sub license, and/or sell copies of the Software, and to
>>>> + * permit persons to whom the Software is furnished to do so, subject to
>>>> + * the following conditions:
>>>> + *
>>>> + * The above copyright notice and this permission notice (including the
>>>> + * next paragraph) shall be included in all copies or substantial portions
>>>> + * of the Software.
>>>> + *
>>>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
>>>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>>>> + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
>>>> + * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
>>>> + * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
>>>> + * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
>>>> + * USE OR OTHER DEALINGS IN THE SOFTWARE.
>>>> + *
>>>> + **************************************************************************/
>>>> +
>>>> +#ifndef _TTM_GLOBAL_H_
>>>> +#define _TTM_GLOBAL_H_
>>>> +
>>>> +#include <drm/drm_global.h>
>>>> +
>>>> +struct ttm_bo_global;
>>>> +
>>>> +/**
>>>> + * struct ttm_global - Stores references to global TTM state
>>>> + */
>>>> +struct ttm_global {
>>>> + struct drm_global_reference mem_ref;
>>>> + struct drm_global_reference bo_ref;
>>>> +};
>>>> +
>>>> +/**
>>>> + * ttm_global_init
>>>> + *
>>>> + * @glob: A pointer to a struct ttm_global that is about to be initialized
>>>> + * @return Zero on success, or a negative error code otherwise.
>>>> + *
>>>> + * Initializes an instance of struct ttm_global with TTM's global state
>>>> + */
>>>> +int ttm_global_init(struct ttm_global *glob);
>>>> +
>>>> +/**
>>>> + * ttm_global_release
>>>> + *
>>>> + * @glob: A pointer to an instance of struct ttm_global
>>>> + *
>>>> + * Releases an initialized instance of struct ttm_global. If the instance
>>>> + * constains the final references to the global memory and BO, the global
>>>> + * structures are released as well.
>>>> + */
>>>> +void ttm_global_release(struct ttm_global *glob);
>>>> +
>>>> +/**
>>>> + * ttm_global_get_bo_global
>>>> + *
>>>> + * @glob A pointer to an instance of struct ttm_global
>>>> + * @return A refernce to the global BO.
>>>> + *
>>>> + * Returns the global BO. The BO should be forwarded to the initialization
>>>> + * of a driver's TTM BO device.
>>>> + */
>>>> +static inline struct ttm_bo_global*
>>>> +ttm_global_get_bo_global(struct ttm_global *glob)
>>>> +{
>>>> + return glob->bo_ref.object;
>>>> +}
>>>> +
>>>> +#endif /* _TTM_GLOBAL_H_ */
>>>> --
>>>> 2.19.1
>>>>
>>> _______________________________________________
>>> dri-devel mailing list
>>> dri-devel at lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>>
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Linux GmbH, Maxfeldstr. 5, D-90409 Nürnberg
>> Tel: +49-911-74053-0; Fax: +49-911-7417755; https://www.suse.com/
>> SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard,
>> Graham Norton, HRB 21284 (AG Nürnberg)
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
>
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