linux-kernel - [PATCH v2 3/4] drm/mode_object: add drm_mode_object_read

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Message-Id: <20241106-drm-small-improvements-v2-3-f6e2aef86719@bootlin.com>
Date: Wed, 06 Nov 2024 11:48:26 +0100
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH v2 3/4] drm/mode_object: add
 drm_mode_object_read_refcount()

Add a wrapper to kref_read() just like the ones already in place for
kref_get() and kref_put(). This will be used for sanity checks on object
lifetime.

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 drivers/gpu/drm/drm_mode_object.c | 20 ++++++++++++++++++++
 include/drm/drm_mode_object.h     |  1 +
 2 files changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c
index df4cc0e8e263d5887a799cf1a61d998234be7158..f990cc7e9b5d3bda3453123593314fa1ea2bf923 100644
--- a/drivers/gpu/drm/drm_mode_object.c
+++ b/drivers/gpu/drm/drm_mode_object.c
@@ -217,6 +217,26 @@ void drm_mode_object_get(struct drm_mode_object *obj)
 }
 EXPORT_SYMBOL(drm_mode_object_get);
 
+/**
+ * drm_mode_object_get - read the refcount for a mode object
+ * @obj: DRM mode object
+ *
+ * This function returns the current object's refcount if it is a
+ * refcounted modeset object, or 0 on any other object.
+ */
+unsigned int drm_mode_object_read_refcount(struct drm_mode_object *obj)
+{
+	unsigned int refcount = 0;
+
+	if (obj->free_cb) {
+		refcount = kref_read(&obj->refcount);
+		DRM_DEBUG("OBJ ID: %d (%d)\n", obj->id, refcount);
+	}
+
+	return refcount;
+}
+EXPORT_SYMBOL(drm_mode_object_read_refcount);
+
 /**
  * drm_object_attach_property - attach a property to a modeset object
  * @obj: drm modeset object
diff --git a/include/drm/drm_mode_object.h b/include/drm/drm_mode_object.h
index c68edbd126d04d51221f50aa2b4166475543b59f..3d2c739e703888bf4520c61594d480f128d50e56 100644
--- a/include/drm/drm_mode_object.h
+++ b/include/drm/drm_mode_object.h
@@ -123,6 +123,7 @@ struct drm_mode_object *drm_mode_object_find(struct drm_device *dev,
 					     uint32_t id, uint32_t type);
 void drm_mode_object_get(struct drm_mode_object *obj);
 void drm_mode_object_put(struct drm_mode_object *obj);
+unsigned int drm_mode_object_read_refcount(struct drm_mode_object *obj);
 
 int drm_object_property_set_value(struct drm_mode_object *obj,
 				  struct drm_property *property,

-- 
2.34.1