[RFC 1/3] drm: Add a way to iterate over minors

[Noralf Trønnes]

Den 10.08.2016 10:43, skrev Daniel Vetter:
> On Tue, Aug 09, 2016 at 07:45:40PM +0200, Noralf Trønnes wrote:
>> This adds a way for in-kernel users to iterate over the available
>> DRM minors. The implementation is oops safe so the panic code
>> can safely use it.
>>
>> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
> Why iterate over minors? I'd kinda have expected we'd iterate over devices
> instead ... And looking ahead, that seems to be what you actually want.

I did this because I couldn't find a list of drm_devices anywhere. Only 
minors.
But I can do a drm_for_each_device() based on the minor "list".

Noralf.

> -Daniel
>
>> ---
>>   drivers/gpu/drm/drm_drv.c | 30 ++++++++++++++++++++++++++++++
>>   include/drm/drmP.h        | 13 +++++++++++++
>>   2 files changed, 43 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
>> index be27ed3..3b14366 100644
>> --- a/drivers/gpu/drm/drm_drv.c
>> +++ b/drivers/gpu/drm/drm_drv.c
>> @@ -292,6 +292,36 @@ void drm_minor_release(struct drm_minor *minor)
>>   }
>>   
>>   /**
>> + * drm_minor_lookup - Lookup DRM minor
>> + * @minor_id: Minor ID of the DRM-minor
>> + *
>> + * Looks up the given minor-ID and returns the respective DRM-minor object.
>> + * No reference is taken on the underlying device.
>> + * See drm_minor_for_each() for iterating over all minors.
>> + *
>> + * Returns:
>> + * Pointer to minor-object or NULL.
>> + */
>> +struct drm_minor *drm_minor_lookup(unsigned int minor_id)
>> +{
>> +	struct drm_minor *minor;
>> +	unsigned long flags;
>> +	int locked = 1;
>> +
>> +	if (oops_in_progress)
>> +		locked = spin_trylock_irqsave(&drm_minor_lock, flags);
>> +	else
>> +		spin_lock_irqsave(&drm_minor_lock, flags);
>> +
>> +	minor = idr_find(&drm_minors_idr, minor_id);
>> +
>> +	if (locked)
>> +		spin_unlock_irqrestore(&drm_minor_lock, flags);
>> +
>> +	return minor;
>> +}
>> +
>> +/**
>>    * DOC: driver instance overview
>>    *
>>    * A device instance for a drm driver is represented by struct &drm_device. This
>> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
>> index d377865..bc7006e 100644
>> --- a/include/drm/drmP.h
>> +++ b/include/drm/drmP.h
>> @@ -974,6 +974,19 @@ void drm_dev_unregister(struct drm_device *dev);
>>   
>>   struct drm_minor *drm_minor_acquire(unsigned int minor_id);
>>   void drm_minor_release(struct drm_minor *minor);
>> +struct drm_minor *drm_minor_lookup(unsigned int minor_id);
>> +
>> +/**
>> + * drm_minor_for_each - Iterate over DRM minors
>> + * @minor: DRM minor handle
>> + * @type: DRM minor type to iterate over
>> + * @id: id handle
>> + *
>> + * Iterate over the registered DRM minors of a given type.
>> + */
>> +#define drm_minor_for_each(minor, type, id)  \
>> +	for ((id) = 0; (id) < 64; (id)++)  \
>> +		if (((minor) = drm_minor_lookup((id) + (type) * 64)))
>>   
>>   /*@}*/
>>   
>> -- 
>> 2.8.2
>>
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