From 98a8883ad419128493b8cfab3982d58785deabda Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 4 Jan 2016 10:11:00 +0000
Subject: [PATCH] drm: Only bump object-reference count when adding first
handle
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We only need a single reference count for all handles (i.e. non-zero
obj->handle_count) and so can trim a few atomic operations by only
taking the reference on the first handle and dropping it after the last.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1451902261-25380-2-git-send-email-chris@chris-wilson.co.uk
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/gpu/drm/drm_gem.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index a08176debc0e..ad955d7c99fd 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -220,6 +220,9 @@ static void drm_gem_object_exported_dma_buf_free(struct drm_gem_object *obj)
static void
drm_gem_object_handle_unreference_unlocked(struct drm_gem_object *obj)
{
+ struct drm_device *dev = obj->dev;
+ bool final = false;
+
if (WARN_ON(obj->handle_count == 0))
return;
@@ -229,14 +232,16 @@ drm_gem_object_handle_unreference_unlocked(struct drm_gem_object *obj)
* checked for a name
*/
- mutex_lock(&obj->dev->object_name_lock);
+ mutex_lock(&dev->object_name_lock);
if (--obj->handle_count == 0) {
drm_gem_object_handle_free(obj);
drm_gem_object_exported_dma_buf_free(obj);
+ final = true;
}
- mutex_unlock(&obj->dev->object_name_lock);
+ mutex_unlock(&dev->object_name_lock);
- drm_gem_object_unreference_unlocked(obj);
+ if (final)
+ drm_gem_object_unreference_unlocked(obj);
}
/**
@@ -329,6 +334,8 @@ drm_gem_handle_create_tail(struct drm_file *file_priv,
int ret;
WARN_ON(!mutex_is_locked(&dev->object_name_lock));
+ if (obj->handle_count++ == 0)
+ drm_gem_object_reference(obj);
/*
* Get the user-visible handle using idr. Preload and perform
@@ -338,10 +345,10 @@ drm_gem_handle_create_tail(struct drm_file *file_priv,
spin_lock(&file_priv->table_lock);
ret = idr_alloc(&file_priv->object_idr, obj, 1, 0, GFP_NOWAIT);
- drm_gem_object_reference(obj);
- obj->handle_count++;
+
spin_unlock(&file_priv->table_lock);
idr_preload_end();
+
mutex_unlock(&dev->object_name_lock);
if (ret < 0)
goto err_unref;
--
2.30.9