From 9ec5df045d320aa2786f85d1548311b61b937036 Mon Sep 17 00:00:00 2001
From: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Date: Fri, 24 Sep 2021 18:38:25 +0200
Subject: drm/i915: Flush buffer pools on driver remove
Git-commit: 74af1e2c16749514fc8db4fc97e59ce897b73fc9
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

We currently do an explicit flush of the buffer pools within the call path
of drm_driver.release(); this removes all buffers, regardless of their age,
freeing the buffers' associated resources (objects, address space areas).
However there is other code that runs within the drm_driver.release() call
chain that expects objects and their associated address space areas have
already been flushed.

Since buffer pools auto-flush old buffers once per second in a worker
thread, there's a small window where if we remove the driver while there
are still objects in buffers with an age of less than one second, the
assumptions of the other release code may be violated.

By moving the flush to driver remove (which executes earlier via the
pci_driver.remove() flow) we're ensuring that all buffers are flushed and
their associated objects freed before some other code in
pci_driver.remove() flushes those objects so they are released before
_any_ code in drm_driver.release() that check completness of those
flushes executes.

v2: Reword commit description as suggested by Matt.

Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210924163825.634606-1-janusz.krzysztofik@linux.intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/gt/intel_gt.c             | 2 ++
 drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c
index 4037c3778225..5b3acf2b064e 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt.c
@@ -741,6 +741,8 @@ void intel_gt_driver_remove(struct intel_gt *gt)
 	intel_uc_driver_remove(&gt->uc);
 
 	intel_engines_release(gt);
+
+	intel_gt_flush_buffer_pool(gt);
 }
 
 void intel_gt_driver_unregister(struct intel_gt *gt)
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c b/drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c
index aa0a59c5b614..acc49c56a9f3 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c
@@ -245,8 +245,6 @@ void intel_gt_fini_buffer_pool(struct intel_gt *gt)
 	struct intel_gt_buffer_pool *pool = &gt->buffer_pool;
 	int n;
 
-	intel_gt_flush_buffer_pool(gt);
-
 	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++)
 		GEM_BUG_ON(!list_empty(&pool->cache_list[n]));
 }
-- 
2.38.1