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![Sylwester Nawrocki](/assets/img/avatar_default.png)
This function allows to remove all media entity's links to other entities, leaving no references to a media entity's links array at its remote entities. Currently, when a driver of some entity is removed it will free its media entities links[] array, leaving dangling pointers at other entities that are part of same media graph. This is troublesome when drivers of a media device entities are in separate kernel modules, removing only some modules will leave others in an incorrect state. This function is intended to be used when an entity is being unregistered from a media device. With an assumption that normally the media links should be created between media entities registered to a media device, with the graph mutex held. Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Sakari Ailus <sakari.ailus@iki.fi> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
634 lines
17 KiB
C
634 lines
17 KiB
C
/*
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* Media entity
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*
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* Copyright (C) 2010 Nokia Corporation
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*
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* Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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* Sakari Ailus <sakari.ailus@iki.fi>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <media/media-entity.h>
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#include <media/media-device.h>
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/**
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* media_entity_init - Initialize a media entity
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*
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* @num_pads: Total number of sink and source pads.
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* @extra_links: Initial estimate of the number of extra links.
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* @pads: Array of 'num_pads' pads.
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*
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* The total number of pads is an intrinsic property of entities known by the
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* entity driver, while the total number of links depends on hardware design
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* and is an extrinsic property unknown to the entity driver. However, in most
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* use cases the entity driver can guess the number of links which can safely
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* be assumed to be equal to or larger than the number of pads.
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*
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* For those reasons the links array can be preallocated based on the entity
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* driver guess and will be reallocated later if extra links need to be
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* created.
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*
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* This function allocates a links array with enough space to hold at least
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* 'num_pads' + 'extra_links' elements. The media_entity::max_links field will
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* be set to the number of allocated elements.
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*
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* The pads array is managed by the entity driver and passed to
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* media_entity_init() where its pointer will be stored in the entity structure.
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*/
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int
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media_entity_init(struct media_entity *entity, u16 num_pads,
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struct media_pad *pads, u16 extra_links)
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{
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struct media_link *links;
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unsigned int max_links = num_pads + extra_links;
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unsigned int i;
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links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
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if (links == NULL)
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return -ENOMEM;
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entity->group_id = 0;
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entity->max_links = max_links;
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entity->num_links = 0;
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entity->num_backlinks = 0;
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entity->num_pads = num_pads;
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entity->pads = pads;
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entity->links = links;
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for (i = 0; i < num_pads; i++) {
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pads[i].entity = entity;
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pads[i].index = i;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(media_entity_init);
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void
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media_entity_cleanup(struct media_entity *entity)
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{
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kfree(entity->links);
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}
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EXPORT_SYMBOL_GPL(media_entity_cleanup);
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/* -----------------------------------------------------------------------------
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* Graph traversal
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*/
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static struct media_entity *
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media_entity_other(struct media_entity *entity, struct media_link *link)
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{
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if (link->source->entity == entity)
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return link->sink->entity;
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else
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return link->source->entity;
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}
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/* push an entity to traversal stack */
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static void stack_push(struct media_entity_graph *graph,
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struct media_entity *entity)
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{
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if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
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WARN_ON(1);
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return;
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}
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graph->top++;
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graph->stack[graph->top].link = 0;
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graph->stack[graph->top].entity = entity;
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}
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static struct media_entity *stack_pop(struct media_entity_graph *graph)
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{
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struct media_entity *entity;
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entity = graph->stack[graph->top].entity;
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graph->top--;
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return entity;
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}
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#define stack_peek(en) ((en)->stack[(en)->top - 1].entity)
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#define link_top(en) ((en)->stack[(en)->top].link)
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#define stack_top(en) ((en)->stack[(en)->top].entity)
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/**
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* media_entity_graph_walk_start - Start walking the media graph at a given entity
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* @graph: Media graph structure that will be used to walk the graph
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* @entity: Starting entity
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*
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* This function initializes the graph traversal structure to walk the entities
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* graph starting at the given entity. The traversal structure must not be
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* modified by the caller during graph traversal. When done the structure can
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* safely be freed.
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*/
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void media_entity_graph_walk_start(struct media_entity_graph *graph,
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struct media_entity *entity)
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{
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graph->top = 0;
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graph->stack[graph->top].entity = NULL;
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stack_push(graph, entity);
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}
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EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
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/**
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* media_entity_graph_walk_next - Get the next entity in the graph
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* @graph: Media graph structure
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*
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* Perform a depth-first traversal of the given media entities graph.
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*
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* The graph structure must have been previously initialized with a call to
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* media_entity_graph_walk_start().
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*
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* Return the next entity in the graph or NULL if the whole graph have been
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* traversed.
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*/
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struct media_entity *
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media_entity_graph_walk_next(struct media_entity_graph *graph)
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{
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if (stack_top(graph) == NULL)
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return NULL;
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/*
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* Depth first search. Push entity to stack and continue from
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* top of the stack until no more entities on the level can be
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* found.
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*/
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while (link_top(graph) < stack_top(graph)->num_links) {
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struct media_entity *entity = stack_top(graph);
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struct media_link *link = &entity->links[link_top(graph)];
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struct media_entity *next;
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/* The link is not enabled so we do not follow. */
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if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
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link_top(graph)++;
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continue;
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}
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/* Get the entity in the other end of the link . */
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next = media_entity_other(entity, link);
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/* Was it the entity we came here from? */
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if (next == stack_peek(graph)) {
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link_top(graph)++;
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continue;
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}
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/* Push the new entity to stack and start over. */
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link_top(graph)++;
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stack_push(graph, next);
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}
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return stack_pop(graph);
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}
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EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
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/* -----------------------------------------------------------------------------
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* Pipeline management
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*/
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/**
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* media_entity_pipeline_start - Mark a pipeline as streaming
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* @entity: Starting entity
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* @pipe: Media pipeline to be assigned to all entities in the pipeline.
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*
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* Mark all entities connected to a given entity through enabled links, either
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* directly or indirectly, as streaming. The given pipeline object is assigned to
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* every entity in the pipeline and stored in the media_entity pipe field.
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*
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* Calls to this function can be nested, in which case the same number of
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* media_entity_pipeline_stop() calls will be required to stop streaming. The
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* pipeline pointer must be identical for all nested calls to
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* media_entity_pipeline_start().
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*/
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__must_check int media_entity_pipeline_start(struct media_entity *entity,
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struct media_pipeline *pipe)
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{
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struct media_device *mdev = entity->parent;
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struct media_entity_graph graph;
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struct media_entity *entity_err = entity;
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int ret;
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mutex_lock(&mdev->graph_mutex);
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media_entity_graph_walk_start(&graph, entity);
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while ((entity = media_entity_graph_walk_next(&graph))) {
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unsigned int i;
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entity->stream_count++;
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WARN_ON(entity->pipe && entity->pipe != pipe);
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entity->pipe = pipe;
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/* Already streaming --- no need to check. */
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if (entity->stream_count > 1)
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continue;
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if (!entity->ops || !entity->ops->link_validate)
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continue;
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for (i = 0; i < entity->num_links; i++) {
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struct media_link *link = &entity->links[i];
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/* Is this pad part of an enabled link? */
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if (!(link->flags & MEDIA_LNK_FL_ENABLED))
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continue;
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/* Are we the sink or not? */
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if (link->sink->entity != entity)
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continue;
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ret = entity->ops->link_validate(link);
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if (ret < 0 && ret != -ENOIOCTLCMD)
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goto error;
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}
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}
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mutex_unlock(&mdev->graph_mutex);
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return 0;
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error:
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/*
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* Link validation on graph failed. We revert what we did and
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* return the error.
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*/
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media_entity_graph_walk_start(&graph, entity_err);
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while ((entity_err = media_entity_graph_walk_next(&graph))) {
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entity_err->stream_count--;
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if (entity_err->stream_count == 0)
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entity_err->pipe = NULL;
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/*
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* We haven't increased stream_count further than this
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* so we quit here.
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*/
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if (entity_err == entity)
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break;
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}
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mutex_unlock(&mdev->graph_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
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/**
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* media_entity_pipeline_stop - Mark a pipeline as not streaming
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* @entity: Starting entity
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*
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* Mark all entities connected to a given entity through enabled links, either
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* directly or indirectly, as not streaming. The media_entity pipe field is
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* reset to NULL.
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*
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* If multiple calls to media_entity_pipeline_start() have been made, the same
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* number of calls to this function are required to mark the pipeline as not
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* streaming.
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*/
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void media_entity_pipeline_stop(struct media_entity *entity)
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{
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struct media_device *mdev = entity->parent;
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struct media_entity_graph graph;
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mutex_lock(&mdev->graph_mutex);
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media_entity_graph_walk_start(&graph, entity);
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while ((entity = media_entity_graph_walk_next(&graph))) {
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entity->stream_count--;
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if (entity->stream_count == 0)
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entity->pipe = NULL;
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}
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mutex_unlock(&mdev->graph_mutex);
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}
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EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
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/* -----------------------------------------------------------------------------
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* Module use count
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*/
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/*
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* media_entity_get - Get a reference to the parent module
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* @entity: The entity
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*
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* Get a reference to the parent media device module.
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*
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* The function will return immediately if @entity is NULL.
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*
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* Return a pointer to the entity on success or NULL on failure.
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*/
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struct media_entity *media_entity_get(struct media_entity *entity)
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{
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if (entity == NULL)
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return NULL;
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if (entity->parent->dev &&
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!try_module_get(entity->parent->dev->driver->owner))
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return NULL;
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return entity;
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}
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EXPORT_SYMBOL_GPL(media_entity_get);
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/*
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* media_entity_put - Release the reference to the parent module
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* @entity: The entity
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*
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* Release the reference count acquired by media_entity_get().
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*
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* The function will return immediately if @entity is NULL.
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*/
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void media_entity_put(struct media_entity *entity)
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{
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if (entity == NULL)
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return;
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if (entity->parent->dev)
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module_put(entity->parent->dev->driver->owner);
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}
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EXPORT_SYMBOL_GPL(media_entity_put);
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/* -----------------------------------------------------------------------------
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* Links management
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*/
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static struct media_link *media_entity_add_link(struct media_entity *entity)
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{
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if (entity->num_links >= entity->max_links) {
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struct media_link *links = entity->links;
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unsigned int max_links = entity->max_links + 2;
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unsigned int i;
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links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
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if (links == NULL)
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return NULL;
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for (i = 0; i < entity->num_links; i++)
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links[i].reverse->reverse = &links[i];
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entity->max_links = max_links;
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entity->links = links;
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}
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return &entity->links[entity->num_links++];
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}
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int
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media_entity_create_link(struct media_entity *source, u16 source_pad,
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struct media_entity *sink, u16 sink_pad, u32 flags)
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{
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struct media_link *link;
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struct media_link *backlink;
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BUG_ON(source == NULL || sink == NULL);
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BUG_ON(source_pad >= source->num_pads);
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BUG_ON(sink_pad >= sink->num_pads);
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link = media_entity_add_link(source);
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if (link == NULL)
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return -ENOMEM;
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link->source = &source->pads[source_pad];
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link->sink = &sink->pads[sink_pad];
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link->flags = flags;
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/* Create the backlink. Backlinks are used to help graph traversal and
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* are not reported to userspace.
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*/
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backlink = media_entity_add_link(sink);
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if (backlink == NULL) {
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source->num_links--;
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return -ENOMEM;
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}
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backlink->source = &source->pads[source_pad];
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backlink->sink = &sink->pads[sink_pad];
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backlink->flags = flags;
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link->reverse = backlink;
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backlink->reverse = link;
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sink->num_backlinks++;
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return 0;
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}
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EXPORT_SYMBOL_GPL(media_entity_create_link);
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void __media_entity_remove_links(struct media_entity *entity)
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{
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unsigned int i;
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for (i = 0; i < entity->num_links; i++) {
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struct media_link *link = &entity->links[i];
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struct media_entity *remote;
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unsigned int r = 0;
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if (link->source->entity == entity)
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remote = link->sink->entity;
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else
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remote = link->source->entity;
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while (r < remote->num_links) {
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struct media_link *rlink = &remote->links[r];
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if (rlink != link->reverse) {
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r++;
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continue;
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}
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if (link->source->entity == entity)
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remote->num_backlinks--;
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if (--remote->num_links == 0)
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break;
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/* Insert last entry in place of the dropped link. */
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*rlink = remote->links[remote->num_links];
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}
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}
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entity->num_links = 0;
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entity->num_backlinks = 0;
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}
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EXPORT_SYMBOL_GPL(__media_entity_remove_links);
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void media_entity_remove_links(struct media_entity *entity)
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{
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/* Do nothing if the entity is not registered. */
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if (entity->parent == NULL)
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return;
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mutex_lock(&entity->parent->graph_mutex);
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__media_entity_remove_links(entity);
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mutex_unlock(&entity->parent->graph_mutex);
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}
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EXPORT_SYMBOL_GPL(media_entity_remove_links);
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static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
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{
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int ret;
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/* Notify both entities. */
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ret = media_entity_call(link->source->entity, link_setup,
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link->source, link->sink, flags);
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if (ret < 0 && ret != -ENOIOCTLCMD)
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return ret;
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ret = media_entity_call(link->sink->entity, link_setup,
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link->sink, link->source, flags);
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if (ret < 0 && ret != -ENOIOCTLCMD) {
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media_entity_call(link->source->entity, link_setup,
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link->source, link->sink, link->flags);
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return ret;
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}
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link->flags = flags;
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link->reverse->flags = link->flags;
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return 0;
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}
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/**
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* __media_entity_setup_link - Configure a media link
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* @link: The link being configured
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* @flags: Link configuration flags
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*
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* The bulk of link setup is handled by the two entities connected through the
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* link. This function notifies both entities of the link configuration change.
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*
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* If the link is immutable or if the current and new configuration are
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* identical, return immediately.
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*
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* The user is expected to hold link->source->parent->mutex. If not,
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* media_entity_setup_link() should be used instead.
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*/
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int __media_entity_setup_link(struct media_link *link, u32 flags)
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{
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const u32 mask = MEDIA_LNK_FL_ENABLED;
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struct media_device *mdev;
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struct media_entity *source, *sink;
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int ret = -EBUSY;
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if (link == NULL)
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return -EINVAL;
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|
|
/* The non-modifiable link flags must not be modified. */
|
|
if ((link->flags & ~mask) != (flags & ~mask))
|
|
return -EINVAL;
|
|
|
|
if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
|
|
return link->flags == flags ? 0 : -EINVAL;
|
|
|
|
if (link->flags == flags)
|
|
return 0;
|
|
|
|
source = link->source->entity;
|
|
sink = link->sink->entity;
|
|
|
|
if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
|
|
(source->stream_count || sink->stream_count))
|
|
return -EBUSY;
|
|
|
|
mdev = source->parent;
|
|
|
|
if (mdev->link_notify) {
|
|
ret = mdev->link_notify(link, flags,
|
|
MEDIA_DEV_NOTIFY_PRE_LINK_CH);
|
|
if (ret < 0)
|
|
return ret;
|
|
}
|
|
|
|
ret = __media_entity_setup_link_notify(link, flags);
|
|
|
|
if (mdev->link_notify)
|
|
mdev->link_notify(link, flags, MEDIA_DEV_NOTIFY_POST_LINK_CH);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int media_entity_setup_link(struct media_link *link, u32 flags)
|
|
{
|
|
int ret;
|
|
|
|
mutex_lock(&link->source->entity->parent->graph_mutex);
|
|
ret = __media_entity_setup_link(link, flags);
|
|
mutex_unlock(&link->source->entity->parent->graph_mutex);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(media_entity_setup_link);
|
|
|
|
/**
|
|
* media_entity_find_link - Find a link between two pads
|
|
* @source: Source pad
|
|
* @sink: Sink pad
|
|
*
|
|
* Return a pointer to the link between the two entities. If no such link
|
|
* exists, return NULL.
|
|
*/
|
|
struct media_link *
|
|
media_entity_find_link(struct media_pad *source, struct media_pad *sink)
|
|
{
|
|
struct media_link *link;
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < source->entity->num_links; ++i) {
|
|
link = &source->entity->links[i];
|
|
|
|
if (link->source->entity == source->entity &&
|
|
link->source->index == source->index &&
|
|
link->sink->entity == sink->entity &&
|
|
link->sink->index == sink->index)
|
|
return link;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(media_entity_find_link);
|
|
|
|
/**
|
|
* media_entity_remote_pad - Find the pad at the remote end of a link
|
|
* @pad: Pad at the local end of the link
|
|
*
|
|
* Search for a remote pad connected to the given pad by iterating over all
|
|
* links originating or terminating at that pad until an enabled link is found.
|
|
*
|
|
* Return a pointer to the pad at the remote end of the first found enabled
|
|
* link, or NULL if no enabled link has been found.
|
|
*/
|
|
struct media_pad *media_entity_remote_pad(struct media_pad *pad)
|
|
{
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < pad->entity->num_links; i++) {
|
|
struct media_link *link = &pad->entity->links[i];
|
|
|
|
if (!(link->flags & MEDIA_LNK_FL_ENABLED))
|
|
continue;
|
|
|
|
if (link->source == pad)
|
|
return link->sink;
|
|
|
|
if (link->sink == pad)
|
|
return link->source;
|
|
}
|
|
|
|
return NULL;
|
|
|
|
}
|
|
EXPORT_SYMBOL_GPL(media_entity_remote_pad);
|