linux-kernel - [PATCH 5.14 075/172] drm/i915/gvt: fix the usage of ww lock in gvt scheduler.

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Date:   Mon,  4 Oct 2021 14:52:05 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Zhi A Wang <zhi.a.wang@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.14 075/172] drm/i915/gvt: fix the usage of ww lock in gvt scheduler.

From: Zhi A Wang <zhi.wang.linux2@...il.com>

[ Upstream commit d168cd797982db9db617113644c87b8f5f3cf27e ]

As the APIs related to ww lock in i915 was changed recently, the usage of
ww lock in GVT-g scheduler needs to be changed accrodingly. We noticed a
deadlock when GVT-g scheduler submits the workload to i915. After some
investigation, it seems the way of how to use ww lock APIs has been
changed. Releasing a ww now requires a explicit i915_gem_ww_ctx_fini().

Fixes: 67f1120381df ("drm/i915/gvt: Introduce per object locking in GVT scheduler.")
Cc: Zhenyu Wang <zhenyuw@...ux.intel.com>
Signed-off-by: Zhi A Wang <zhi.a.wang@...el.com>
Signed-off-by: Zhenyu Wang <zhenyuw@...ux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20210826143834.25410-1-zhi.a.wang@intel.com
Acked-by: Zhenyu Wang <zhenyuw@...ux.intel.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/i915/gvt/scheduler.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index 734c37c5e347..527b59b86312 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -576,7 +576,7 @@ static int prepare_shadow_batch_buffer(struct intel_vgpu_workload *workload)
 
 			/* No one is going to touch shadow bb from now on. */
 			i915_gem_object_flush_map(bb->obj);
-			i915_gem_object_unlock(bb->obj);
+			i915_gem_ww_ctx_fini(&ww);
 		}
 	}
 	return 0;
@@ -630,7 +630,7 @@ static int prepare_shadow_wa_ctx(struct intel_shadow_wa_ctx *wa_ctx)
 		return ret;
 	}
 
-	i915_gem_object_unlock(wa_ctx->indirect_ctx.obj);
+	i915_gem_ww_ctx_fini(&ww);
 
 	/* FIXME: we are not tracking our pinned VMA leaving it
 	 * up to the core to fix up the stray pin_count upon
-- 
2.33.0