From 663a50ceac75c2208d2ad95365bc8382fd42f44d Mon Sep 17 00:00:00 2001
From: Yan Zhao <yan.y.zhao@intel.com>
Date: Wed, 27 Mar 2019 00:55:45 -0400
Subject: [PATCH] drm/i915/gvt: do not let pin count of shadow mm go negative
shadow mm's pin count got increased in workload preparation phase, which
is after workload scanning.
it will get decreased in complete_current_workload() anyway after
workload completion.
Sometimes, if a workload meets a scanning error, its shadow mm pin count
will not get increased but will get decreased in the end.
This patch lets shadow mm's pin count not go below 0.
Fixes: 2707e4446688 ("drm/i915/gvt: vGPU graphics memory virtualization")
Cc: zhenyuw@linux.intel.com
Cc: stable@vger.kernel.org #4.14+
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
---
drivers/gpu/drm/i915/gvt/gtt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index d7052ab7908c8..cf133ef038735 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -1946,7 +1946,7 @@ void _intel_vgpu_mm_release(struct kref *mm_ref)
*/
void intel_vgpu_unpin_mm(struct intel_vgpu_mm *mm)
{
- atomic_dec(&mm->pincount);
+ atomic_dec_if_positive(&mm->pincount);
}
/**
--
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