linux-kernel - [PATCH v3] drm/amd/display: Fix exception handling in dm_validate_stream_and

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Message-ID: <8684e2ba-b644-44c8-adf7-9f1423a1251d@web.de>
Date: Tue, 10 Jun 2025 08:10:41 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 Alex Deucher <alexander.deucher@....com>, Alex Hung <alex.hung@....com>,
 Aurabindo Pillai <aurabindo.pillai@....com>,
 Christian König <christian.koenig@....com>,
 Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...il.com>,
 Dominik Kaszewski <dominik.kaszewski@....com>,
 Fangzhi Zuo <Jerry.Zuo@....com>, Harry Wentland <harry.wentland@....com>,
 Leo Li <sunpeng.li@....com>, Mario Limonciello <mario.limonciello@....com>,
 Roman Li <roman.li@....com>, Simona Vetter <simona@...ll.ch>,
 Tom Chung <chiahsuan.chung@....com>, Wayne Lin <Wayne.Lin@....com>
Cc: LKML <linux-kernel@...r.kernel.org>, kernel-janitors@...r.kernel.org,
 lkp@...el.com, oe-kbuild-all@...ts.linux.dev, llvm@...ts.linux.dev,
 cocci@...ia.fr, Melissa Wen <mwen@...lia.com>
Subject: [PATCH v3] drm/amd/display: Fix exception handling in
 dm_validate_stream_and_context()

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Tue, 10 Jun 2025 07:42:40 +0200

The label “cleanup” was used to jump to another pointer check despite of
the detail in the implementation of the function “dm_validate_stream_and_context”
that it was determined already that corresponding variables contained
still null pointers.

1. Thus return directly if
   * a null pointer was passed for the function parameter “stream”
     or
   * a call of the function “dc_create_plane_state” failed.

2. Use a more appropriate label instead.

3. Delete two questionable checks.

4. Omit extra initialisations (for the variables “dc_state” and “dc_plane_state”)
   which became unnecessary with this refactoring.


This issue was detected by using the Coccinelle software.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202506100312.Ms4XgAzW-lkp@intel.com/
Fixes: 5468c36d6285 ("drm/amd/display: Filter Invalid 420 Modes for HDMI TMDS")
Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---

V3:
* Another function call was renamed.

* Recipient lists were adjusted once more.

V2:
* The change suggestion was rebased on source files of
  the software “Linux next-20250606”.

* Recipient lists were adjusted accordingly.


 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 20 ++++++++-----------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 78816712afbb..7dc80b2fbd30 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -7473,19 +7473,19 @@ static enum dc_status dm_validate_stream_and_context(struct dc *dc,
 						struct dc_stream_state *stream)
 {
 	enum dc_status dc_result = DC_ERROR_UNEXPECTED;
-	struct dc_plane_state *dc_plane_state = NULL;
-	struct dc_state *dc_state = NULL;
+	struct dc_plane_state *dc_plane_state;
+	struct dc_state *dc_state;
 
 	if (!stream)
-		goto cleanup;
+		return dc_result;
 
 	dc_plane_state = dc_create_plane_state(dc);
 	if (!dc_plane_state)
-		goto cleanup;
+		return dc_result;
 
 	dc_state = dc_state_create(dc, NULL);
 	if (!dc_state)
-		goto cleanup;
+		goto release_plane_state;
 
 	/* populate stream to plane */
 	dc_plane_state->src_rect.height  = stream->src.height;
@@ -7522,13 +7522,9 @@ static enum dc_status dm_validate_stream_and_context(struct dc *dc,
 	if (dc_result == DC_OK)
 		dc_result = dc_validate_global_state(dc, dc_state, DC_VALIDATE_MODE_ONLY);
 
-cleanup:
-	if (dc_state)
-		dc_state_release(dc_state);
-
-	if (dc_plane_state)
-		dc_plane_state_release(dc_plane_state);
-
+	dc_state_release(dc_state);
+release_plane_state:
+	dc_plane_state_release(dc_plane_state);
 	return dc_result;
 }
 
-- 
2.49.0