[PATCH v4 01/11] drm/bridge: drm_bridge_get/put(): ignore ERR_PTR

[Luca Ceresoli]

Most functions returning a struct drm_bridge pointer currently return a
valid pointer or NULL, but this restricts their ability to return an error
code describing the error kind.

In preparation to have new APIs that can return a struct drm_bridge pointer
holding an ERR_PTR (and for those which already do) make drm_bridge_get()
and drm_bridge_put() ignore ERR_PTR values, just like they ignore NULL
pointers.

This will avoid annoying error checking in many places and the risk of
missing error checks.

Suggested-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Link: https://lore.kernel.org/all/20260318152533.GA633439@killaraus.ideasonboard.com/
Suggested-by: Dmitry Baryshkov <dmitry.baryshkov at oss.qualcomm.com>
Link: https://lore.kernel.org/all/omlnswxukeqgnatzdvooaashgkfcacjevkvbkm6xt33itgua2k@jcmzll2w6kdq/
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov at oss.qualcomm.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli at bootlin.com>
---

Changes in v4:
- removed incorrect change to drm_bridge_clear_and_put() kdoc

Patch added in v2
---
 drivers/gpu/drm/drm_bridge.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index d4b3478258ec..6fb71de6d22a 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -282,7 +282,7 @@ static void __drm_bridge_free(struct kref *kref)
 
 /**
  * drm_bridge_get - Acquire a bridge reference
- * @bridge: DRM bridge; if NULL this function does nothing
+ * @bridge: DRM bridge; if NULL or an ERR_PTR this function does nothing
  *
  * This function increments the bridge's refcount.
  *
@@ -291,7 +291,7 @@ static void __drm_bridge_free(struct kref *kref)
  */
 struct drm_bridge *drm_bridge_get(struct drm_bridge *bridge)
 {
-	if (bridge)
+	if (!IS_ERR_OR_NULL(bridge))
 		kref_get(&bridge->refcount);
 
 	return bridge;
@@ -300,7 +300,7 @@ EXPORT_SYMBOL(drm_bridge_get);
 
 /**
  * drm_bridge_put - Release a bridge reference
- * @bridge: DRM bridge; if NULL this function does nothing
+ * @bridge: DRM bridge; if NULL or an ERR_PTR this function does nothing
  *
  * This function decrements the bridge's reference count and frees the
  * object if the reference count drops to zero.
@@ -310,7 +310,7 @@ EXPORT_SYMBOL(drm_bridge_get);
  */
 void drm_bridge_put(struct drm_bridge *bridge)
 {
-	if (bridge)
+	if (!IS_ERR_OR_NULL(bridge))
 		kref_put(&bridge->refcount, __drm_bridge_free);
 }
 EXPORT_SYMBOL(drm_bridge_put);

-- 
2.53.0