linux-kernel - [PATCH 2/3] drm/bridge: select_bus_fmt_recursive(): put the bridge obtained by drm_bridge_get_prev

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Message-Id: <20250709-drm-bridge-alloc-getput-drm_bridge_get_prev_bridge-v1-2-34ba6f395aaa@bootlin.com>
Date: Wed, 09 Jul 2025 17:59:38 +0200
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>, 
 Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 2/3] drm/bridge: select_bus_fmt_recursive(): put the bridge
 obtained by drm_bridge_get_prev_bridge()

The bridge returned by drm_bridge_get_prev_bridge() is refcounted. Put it
when done.

select_bus_fmt_recursive() has several return points, and ensuring
drm_bridge_put() is always called in the right place would be error-prone
(especially with future changes to the select_bus_fmt_recursive() code) and
make code uglier. Instead use a scope-based free, which is future-proof and
a lot cleaner.

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 drivers/gpu/drm/drm_bridge.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 0b450b334afd82e0460f18fdd248f79d0a2b153d..e33ccc5cabab72505b839d23bfa5ae644d2105c4 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -941,11 +941,11 @@ static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
 {
 	unsigned int i, num_in_bus_fmts = 0;
 	struct drm_bridge_state *cur_state;
-	struct drm_bridge *prev_bridge;
+	struct drm_bridge *prev_bridge __free(drm_bridge_put) =
+		drm_bridge_get_prev_bridge(cur_bridge);
 	u32 *in_bus_fmts;
 	int ret;
 
-	prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
 	cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
 						    cur_bridge);
 

-- 
2.50.0