linux-kernel - [PATCH] drm/amdgpu/display: Fix an error handling path in 'dm_update_crtc

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Date:   Sun,  8 Mar 2020 10:26:37 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     harry.wentland@....com, sunpeng.li@....com,
        alexander.deucher@....com, christian.koenig@....com,
        David1.Zhou@....com, airlied@...ux.ie, daniel@...ll.ch,
        nicholas.kazlauskas@....com, Bhawanpreet.Lakha@....com,
        mario.kleiner.de@...il.com, David.Francis@....com
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] drm/amdgpu/display: Fix an error handling path in 'dm_update_crtc_state()'

'dc_stream_release()' may be called twice. Once here, and once below in the
error handling path if we branch to the 'fail' label.

Set 'new_stream' to NULL, once released to avoid the duplicated release
function call.

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Maybe the 'goto fail' at line 7745 should be turned into a 'return ret'
instead. Could be clearer.

No Fixes tag provided because I've not been able to dig deep enough in the
git history.
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 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 97c1b01c0fc1..9d7773a77c4f 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -7704,8 +7704,10 @@ static int dm_update_crtc_state(struct amdgpu_display_manager *dm,
 
 skip_modeset:
 	/* Release extra reference */
-	if (new_stream)
-		 dc_stream_release(new_stream);
+	if (new_stream) {
+		dc_stream_release(new_stream);
+		new_stream = NULL;
+	}
 
 	/*
 	 * We want to do dc stream updates that do not require a
-- 
2.20.1