Re: [Intel-gfx] [PATCH 1/2] drm/drm_vma_manager: Add drm_vma_node_allow_once()

["Das, Nirmoy" <nirmoy.das@linux.intel.com>]

On 1/18/2023 10:38 AM, Andi Shyti wrote:
> On Tue, Jan 17, 2023 at 06:52:35PM +0100, Nirmoy Das wrote:
>> Currently there is no easy way for a drm driver to safely check and allow
>> drm_vma_offset_node for a drm file just once. Allow drm drivers to call
>> non-refcounted version of drm_vma_node_allow() so that a driver doesn't
>> need to keep track of each drm_vma_node_allow() to call subsequent
>> drm_vma_node_revoke() to prevent memory leak.
>>
>> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> Cc: Maxime Ripard <mripard@kernel.org>
>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>> Cc: David Airlie <airlied@gmail.com>
>> Cc: Daniel Vetter <daniel@ffwll.ch>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
>> Cc: Andi Shyti <andi.shyti@linux.intel.com>
>>
> Next time, please, don't leave any spaces between tags.


I will keep that in my mind.

>
>> Suggested-by: Chris Wilson <chris.p.wilson@intel.com>
>> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>


Thanks,

Nirmoy

>
> Thanks,
> Andi
>
>> ---
>>   drivers/gpu/drm/drm_vma_manager.c | 76 ++++++++++++++++++++++---------
>>   include/drm/drm_vma_manager.h     |  1 +
>>   2 files changed, 55 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_vma_manager.c b/drivers/gpu/drm/drm_vma_manager.c
>> index 7de37f8c68fd..83229a031af0 100644
>> --- a/drivers/gpu/drm/drm_vma_manager.c
>> +++ b/drivers/gpu/drm/drm_vma_manager.c
>> @@ -240,27 +240,8 @@ void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,
>>   }
>>   EXPORT_SYMBOL(drm_vma_offset_remove);
>>   
>> -/**
>> - * drm_vma_node_allow - Add open-file to list of allowed users
>> - * @node: Node to modify
>> - * @tag: Tag of file to remove
>> - *
>> - * Add @tag to the list of allowed open-files for this node. If @tag is
>> - * already on this list, the ref-count is incremented.
>> - *
>> - * The list of allowed-users is preserved across drm_vma_offset_add() and
>> - * drm_vma_offset_remove() calls. You may even call it if the node is currently
>> - * not added to any offset-manager.
>> - *
>> - * You must remove all open-files the same number of times as you added them
>> - * before destroying the node. Otherwise, you will leak memory.
>> - *
>> - * This is locked against concurrent access internally.
>> - *
>> - * RETURNS:
>> - * 0 on success, negative error code on internal failure (out-of-mem)
>> - */
>> -int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag)
>> +static int vma_node_allow(struct drm_vma_offset_node *node,
>> +			  struct drm_file *tag, bool ref_counted)
>>   {
>>   	struct rb_node **iter;
>>   	struct rb_node *parent = NULL;
>> @@ -282,7 +263,8 @@ int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag)
>>   		entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb);
>>   
>>   		if (tag == entry->vm_tag) {
>> -			entry->vm_count++;
>> +			if (ref_counted)
>> +				entry->vm_count++;
>>   			goto unlock;
>>   		} else if (tag > entry->vm_tag) {
>>   			iter = &(*iter)->rb_right;
>> @@ -307,8 +289,58 @@ int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag)
>>   	kfree(new);
>>   	return ret;
>>   }
>> +
>> +/**
>> + * drm_vma_node_allow - Add open-file to list of allowed users
>> + * @node: Node to modify
>> + * @tag: Tag of file to remove
>> + *
>> + * Add @tag to the list of allowed open-files for this node. If @tag is
>> + * already on this list, the ref-count is incremented.
>> + *
>> + * The list of allowed-users is preserved across drm_vma_offset_add() and
>> + * drm_vma_offset_remove() calls. You may even call it if the node is currently
>> + * not added to any offset-manager.
>> + *
>> + * You must remove all open-files the same number of times as you added them
>> + * before destroying the node. Otherwise, you will leak memory.
>> + *
>> + * This is locked against concurrent access internally.
>> + *
>> + * RETURNS:
>> + * 0 on success, negative error code on internal failure (out-of-mem)
>> + */
>> +int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag)
>> +{
>> +	return vma_node_allow(node, tag, true);
>> +}
>>   EXPORT_SYMBOL(drm_vma_node_allow);
>>   
>> +/**
>> + * drm_vma_node_allow_once - Add open-file to list of allowed users
>> + * @node: Node to modify
>> + * @tag: Tag of file to remove
>> + *
>> + * Add @tag to the list of allowed open-files for this node.
>> + *
>> + * The list of allowed-users is preserved across drm_vma_offset_add() and
>> + * drm_vma_offset_remove() calls. You may even call it if the node is currently
>> + * not added to any offset-manager.
>> + *
>> + * This is not ref-counted unlike drm_vma_node_allow() hence drm_vma_node_revoke()
>> + * should only be called once after this.
>> + *
>> + * This is locked against concurrent access internally.
>> + *
>> + * RETURNS:
>> + * 0 on success, negative error code on internal failure (out-of-mem)
>> + */
>> +int drm_vma_node_allow_once(struct drm_vma_offset_node *node, struct drm_file *tag)
>> +{
>> +	return vma_node_allow(node, tag, false);
>> +}
>> +EXPORT_SYMBOL(drm_vma_node_allow_once);
>> +
>>   /**
>>    * drm_vma_node_revoke - Remove open-file from list of allowed users
>>    * @node: Node to modify
>> diff --git a/include/drm/drm_vma_manager.h b/include/drm/drm_vma_manager.h
>> index 4f8c35206f7c..6c2a2f21dbf0 100644
>> --- a/include/drm/drm_vma_manager.h
>> +++ b/include/drm/drm_vma_manager.h
>> @@ -74,6 +74,7 @@ void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,
>>   			   struct drm_vma_offset_node *node);
>>   
>>   int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag);
>> +int drm_vma_node_allow_once(struct drm_vma_offset_node *node, struct drm_file *tag);
>>   void drm_vma_node_revoke(struct drm_vma_offset_node *node,
>>   			 struct drm_file *tag);
>>   bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,
>> -- 
>> 2.39.0