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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, Lang Yu <Lang.Yu@amd.com>,
        Roman Li <Roman.Li@amd.com>,
        Qingqing Zhuo <Qingqing.Zhuo@amd.com>,
        Wayne Lin <Wayne.Lin@amd.com>,
        Daniel Wheeler <daniel.wheeler@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.12 368/700] drm/amd/display: fix potential gpu reset deadlock
Date:   Mon, 12 Jul 2021 08:07:31 +0200
Message-Id: <20210712061015.544855284@linuxfoundation.org>
In-Reply-To: <20210712060924.797321836@linuxfoundation.org>
References: <20210712060924.797321836@linuxfoundation.org>
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From: Roman Li <Roman.Li@amd.com>

[ Upstream commit cf8b92a75646735136053ce51107bfa8cfc23191 ]

[Why]
In gpu reset dc_lock acquired in dm_suspend().
Asynchronously handle_hpd_rx_irq can also be called
through amdgpu_dm_irq_suspend->flush_work, which also
tries to acquire dc_lock. That causes a deadlock.

[How]
Check if amdgpu executing reset before acquiring dc_lock.

Signed-off-by: Lang Yu <Lang.Yu@amd.com>
Signed-off-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Qingqing Zhuo <Qingqing.Zhuo@amd.com>
Acked-by: Wayne Lin <Wayne.Lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@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.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 eed494630583..d95569e0e53a 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2624,13 +2624,15 @@ static void handle_hpd_rx_irq(void *param)
 		}
 	}
 
-	mutex_lock(&adev->dm.dc_lock);
+	if (!amdgpu_in_reset(adev))
+		mutex_lock(&adev->dm.dc_lock);
 #ifdef CONFIG_DRM_AMD_DC_HDCP
 	result = dc_link_handle_hpd_rx_irq(dc_link, &hpd_irq_data, NULL);
 #else
 	result = dc_link_handle_hpd_rx_irq(dc_link, NULL, NULL);
 #endif
-	mutex_unlock(&adev->dm.dc_lock);
+	if (!amdgpu_in_reset(adev))
+		mutex_unlock(&adev->dm.dc_lock);
 
 out:
 	if (result && !is_mst_root_connector) {
-- 
2.30.2