Relax the spinlock used for looking up the handle in the XArray and
acquiring a reference to it to an RCU protected critical section. This
incurs the requirement that we protect the syncobj struct itself using
RCU, which we achieve by simply calling kfree_rcu() and being more
careful in acquiring our reference.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
drivers/gpu/drm/drm_syncobj.c | 12 +++++-------
include/drm/drm_syncobj.h | 2 ++
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 4fc71dc9fc43..aafc03986a48 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -86,13 +86,11 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
{
struct drm_syncobj *syncobj;
- xa_lock(&file_private->syncobjs);
-
+ rcu_read_lock();
syncobj = xa_load(&file_private->syncobjs, handle);
- if (syncobj)
- drm_syncobj_get(syncobj);
-
- xa_unlock(&file_private->syncobjs);
+ if (syncobj && !kref_get_unless_zero(&syncobj->refcount))
+ syncobj = NULL;
+ rcu_read_unlock();
return syncobj;
}
@@ -309,7 +307,7 @@ void drm_syncobj_free(struct kref *kref)
struct drm_syncobj,
refcount);
drm_syncobj_replace_fence(syncobj, NULL);
- kfree(syncobj);
+ kfree_rcu(syncobj, rcu);
}
EXPORT_SYMBOL(drm_syncobj_free);
diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
index 6cf7243a1dc5..7c1503d47abf 100644
--- a/include/drm/drm_syncobj.h
+++ b/include/drm/drm_syncobj.h
@@ -61,6 +61,8 @@ struct drm_syncobj {
* @file: A file backing for this syncobj.
*/
struct file *file;
+
+ struct rcu_head rcu;
};
void drm_syncobj_free(struct kref *kref);
--
2.23.0.rc0
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