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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, Shirish S <shirish.s@amd.com>,
        =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
        Andrey Grodzovsky <andrey.grodzovsky@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.3 077/135] drm/amdgpu: dont schedule jobs while in reset
Date:   Tue,  3 Dec 2019 23:35:17 +0100
Message-Id: <20191203213029.135880551@linuxfoundation.org>
In-Reply-To: <20191203213005.828543156@linuxfoundation.org>
References: <20191203213005.828543156@linuxfoundation.org>
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From: Shirish S <shirish.s@amd.com>

[ Upstream commit f2efc6e60089c99c342a6b7da47f1037e06c4296 ]

[Why]

doing kthread_park()/unpark() from drm_sched_entity_fini
while GPU reset is in progress defeats all the purpose of
drm_sched_stop->kthread_park.
If drm_sched_entity_fini->kthread_unpark() happens AFTER
drm_sched_stop->kthread_park nothing prevents from another
(third) thread to keep submitting job to HW which will be
picked up by the unparked scheduler thread and try to submit
to HW but fail because the HW ring is deactivated.

[How]
grab the reset lock before calling drm_sched_entity_fini()

Signed-off-by: Shirish S <shirish.s@amd.com>
Suggested-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
index 7398b4850649b..b7633484d15f2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
@@ -597,8 +597,11 @@ void amdgpu_ctx_mgr_entity_fini(struct amdgpu_ctx_mgr *mgr)
 			continue;
 		}
 
-		for (i = 0; i < num_entities; i++)
+		for (i = 0; i < num_entities; i++) {
+			mutex_lock(&ctx->adev->lock_reset);
 			drm_sched_entity_fini(&ctx->entities[0][i].entity);
+			mutex_unlock(&ctx->adev->lock_reset);
+		}
 	}
 }
 
-- 
2.20.1