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drm/syncobj: Add a callback mechanism for replace_fence (v3) 

It is useful in certain circumstances to know when the fence is replaced
in a syncobj.  Specifically, it may be useful to know when the fence
goes from NULL to something valid.  This does make syncobj_replace_fence
a little more expensive because it has to take a lock but, in the common
case where there is no callback list, it spends a very short amount of
time inside the lock.

v2:
 - Don't lock in drm_syncobj_fence_get.  We only really need to lock
   around fence_replace to make the callback work.
v3:
 - Fix the cb_list comment to make kbuild happy

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Jason Ekstrand 2017-08-28 07:39:25 -07:00 committed by Dave Airlie
parent 5e60a10eae
commit 9c19fb10a5
2 changed files with 97 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
drivers/gpu/drm/drm_syncobj.c
View File

@ -80,6 +80,46 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
}
EXPORT_SYMBOL(drm_syncobj_find);
static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
struct drm_syncobj_cb *cb,
drm_syncobj_func_t func)
{
cb->func = func;
list_add_tail(&cb->node, &syncobj->cb_list);
}
/**
* drm_syncobj_add_callback - adds a callback to syncobj::cb_list
* @syncobj: Sync object to which to add the callback
* @cb: Callback to add
* @func: Func to use when initializing the drm_syncobj_cb struct
*
* This adds a callback to be called next time the fence is replaced
*/
void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
struct drm_syncobj_cb *cb,
drm_syncobj_func_t func)
{
spin_lock(&syncobj->lock);
drm_syncobj_add_callback_locked(syncobj, cb, func);
spin_unlock(&syncobj->lock);
}
EXPORT_SYMBOL(drm_syncobj_add_callback);
/**
* drm_syncobj_add_callback - removes a callback to syncobj::cb_list
* @syncobj: Sync object from which to remove the callback
* @cb: Callback to remove
*/
void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
struct drm_syncobj_cb *cb)
{
spin_lock(&syncobj->lock);
list_del_init(&cb->node);
spin_unlock(&syncobj->lock);
}
EXPORT_SYMBOL(drm_syncobj_remove_callback);
/**
* drm_syncobj_replace_fence - replace fence in a sync object.
* @syncobj: Sync object to replace fence in
@ -91,10 +131,24 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
struct dma_fence *fence)
{
struct dma_fence *old_fence;
struct drm_syncobj_cb *cur, *tmp;
if (fence)
dma_fence_get(fence);
old_fence = xchg(&syncobj->fence, fence);
spin_lock(&syncobj->lock);
old_fence = syncobj->fence;
syncobj->fence = fence;
if (fence != old_fence) {
list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) {
list_del_init(&cur->node);
cur->func(syncobj, cur);
}
}
spin_unlock(&syncobj->lock);
dma_fence_put(old_fence);
}
@ -130,7 +184,7 @@ void drm_syncobj_free(struct kref *kref)
struct drm_syncobj *syncobj = container_of(kref,
struct drm_syncobj,
refcount);
dma_fence_put(syncobj->fence);
drm_syncobj_replace_fence(syncobj, NULL);
kfree(syncobj);
}
EXPORT_SYMBOL(drm_syncobj_free);
@ -146,6 +200,8 @@ static int drm_syncobj_create(struct drm_file *file_private,
return -ENOMEM;
kref_init(&syncobj->refcount);
INIT_LIST_HEAD(&syncobj->cb_list);
spin_lock_init(&syncobj->lock);
idr_preload(GFP_KERNEL);
spin_lock(&file_private->syncobj_table_lock);

39
include/drm/drm_syncobj.h
View File

@ -28,6 +28,8 @@
#include "linux/dma-fence.h"
struct drm_syncobj_cb;
/**
* struct drm_syncobj - sync object.
*
@ -43,8 +45,21 @@ struct drm_syncobj {
/**
* @fence:
* NULL or a pointer to the fence bound to this object.
*
* This field should not be used directly. Use drm_syncobj_fence_get
* and drm_syncobj_replace_fence instead.
*/
struct dma_fence *fence;
/**
* @cb_list:
* List of callbacks to call when the fence gets replaced
*/
struct list_head cb_list;
/**
* @lock:
* locks cb_list and write-locks fence.
*/
spinlock_t lock;
/**
* @file:
* a file backing for this syncobj.
@ -52,6 +67,25 @@ struct drm_syncobj {
struct file *file;
};
typedef void (*drm_syncobj_func_t)(struct drm_syncobj *syncobj,
struct drm_syncobj_cb *cb);
/**
* struct drm_syncobj_cb - callback for drm_syncobj_add_callback
* @node: used by drm_syncob_add_callback to append this struct to
* syncobj::cb_list
* @func: drm_syncobj_func_t to call
*
* This struct will be initialized by drm_syncobj_add_callback, additional
* data can be passed along by embedding drm_syncobj_cb in another struct.
* The callback will get called the next time drm_syncobj_replace_fence is
* called.
*/
struct drm_syncobj_cb {
struct list_head node;
drm_syncobj_func_t func;
};
void drm_syncobj_free(struct kref *kref);
/**
@ -91,6 +125,11 @@ drm_syncobj_fence_get(struct drm_syncobj *syncobj)
struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
u32 handle);
void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
struct drm_syncobj_cb *cb,
drm_syncobj_func_t func);
void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
struct drm_syncobj_cb *cb);
void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
struct dma_fence *fence);
int drm_syncobj_find_fence(struct drm_file *file_private,