linux-kernel - [PATCH AUTOSEL 6.5 31/52] drm/ttm: Reorder sys manager cleanup step

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Message-ID: <20231029225441.789781-31-sashal@kernel.org>
Date:   Sun, 29 Oct 2023 18:53:18 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Karolina Stolarek <karolina.stolarek@...el.com>,
        Christian König <christian.koenig@....com>,
        Sasha Levin <sashal@...nel.org>, ray.huang@....com,
        airlied@...il.com, daniel@...ll.ch, dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.5 31/52] drm/ttm: Reorder sys manager cleanup step

From: Karolina Stolarek <karolina.stolarek@...el.com>

[ Upstream commit 3b401e30c249849d803de6c332dad2a595a58658 ]

With the current cleanup flow, we could trigger a NULL pointer
dereference if there is a delayed destruction of a BO with a
system resource that gets executed on drain_workqueue() call,
as we attempt to free a resource using an already released
resource manager.

Remove the device from the device list and drain its workqueue
before releasing the system domain manager in ttm_device_fini().

Signed-off-by: Karolina Stolarek <karolina.stolarek@...el.com>
Reviewed-by: Christian König <christian.koenig@....com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231016121525.2237838-1-karolina.stolarek@intel.com
Signed-off-by: Christian König <christian.koenig@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/ttm/ttm_device.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
index 7726a72befc54..d48b39132b324 100644
--- a/drivers/gpu/drm/ttm/ttm_device.c
+++ b/drivers/gpu/drm/ttm/ttm_device.c
@@ -232,10 +232,6 @@ void ttm_device_fini(struct ttm_device *bdev)
 	struct ttm_resource_manager *man;
 	unsigned i;
 
-	man = ttm_manager_type(bdev, TTM_PL_SYSTEM);
-	ttm_resource_manager_set_used(man, false);
-	ttm_set_driver_manager(bdev, TTM_PL_SYSTEM, NULL);
-
 	mutex_lock(&ttm_global_mutex);
 	list_del(&bdev->device_list);
 	mutex_unlock(&ttm_global_mutex);
@@ -243,6 +239,10 @@ void ttm_device_fini(struct ttm_device *bdev)
 	drain_workqueue(bdev->wq);
 	destroy_workqueue(bdev->wq);
 
+	man = ttm_manager_type(bdev, TTM_PL_SYSTEM);
+	ttm_resource_manager_set_used(man, false);
+	ttm_set_driver_manager(bdev, TTM_PL_SYSTEM, NULL);
+
 	spin_lock(&bdev->lru_lock);
 	for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i)
 		if (list_empty(&man->lru[0]))
-- 
2.42.0