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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, kernel test robot <lkp@intel.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>,
        Pavle Kotarac <Pavle.Kotarac@amd.com>,
        Wayne Lin <Wayne.Lin@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 219/846] drm/amd/display: Fix bug in debugfs crc_win_update entry
Date:   Mon, 24 Jan 2022 19:35:36 +0100
Message-Id: <20220124184108.479174958@linuxfoundation.org>
In-Reply-To: <20220124184100.867127425@linuxfoundation.org>
References: <20220124184100.867127425@linuxfoundation.org>
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From: Wayne Lin <Wayne.Lin@amd.com>

[ Upstream commit 4bef85d4c9491415b7931407b07f24841c1e0390 ]

[Why]
crc_rd_wrk shouldn't be null in crc_win_update_set(). Current programming
logic is inconsistent in crc_win_update_set().

[How]
Initially, return if crc_rd_wrk is NULL. Later on, we can use member of
crc_rd_wrk safely.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 9a65df193108 ("drm/amd/display: Use PSP TA to read out crc")

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@amd.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
index de9ec5ddb6c72..e94ddd5e7b638 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
@@ -2908,10 +2908,13 @@ static int crc_win_update_set(void *data, u64 val)
 	struct amdgpu_device *adev = drm_to_adev(new_crtc->dev);
 	struct crc_rd_work *crc_rd_wrk = adev->dm.crc_rd_wrk;
 
+	if (!crc_rd_wrk)
+		return 0;
+
 	if (val) {
 		spin_lock_irq(&adev_to_drm(adev)->event_lock);
 		spin_lock_irq(&crc_rd_wrk->crc_rd_work_lock);
-		if (crc_rd_wrk && crc_rd_wrk->crtc) {
+		if (crc_rd_wrk->crtc) {
 			old_crtc = crc_rd_wrk->crtc;
 			old_acrtc = to_amdgpu_crtc(old_crtc);
 		}
-- 
2.34.1