linux-kernel - [PATCH 5.19 17/38] drm/i915/guc: Cancel GuC engine busyness worker synchronously

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Date:   Wed, 21 Sep 2022 17:46:01 +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,
        Umesh Nerlige Ramappa <umesh.nerlige.ramappa@...el.com>,
        Ashutosh Dixit <ashutosh.dixit@...el.com>,
        John Harrison <John.C.Harrison@...el.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.19 17/38] drm/i915/guc: Cancel GuC engine busyness worker synchronously

From: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@...el.com>

[ Upstream commit aee5ae7c8492eaca2be20d202887c9c716ffc86f ]

The worker is canceled in gt_park path, but earlier it was assumed that
gt_park path cannot sleep and the cancel is asynchronous. This caused a
race with suspend flow where the worker runs after suspend and causes an
unclaimed register access warning. Cancel the worker synchronously since
the gt_park is indeed allowed to sleep.

v2: Fix author name and sign-off mismatch

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@...el.com>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4419
Fixes: 77cdd054dd2c ("drm/i915/pmu: Connect engine busyness stats from GuC to pmu")
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@...el.com>
Signed-off-by: John Harrison <John.C.Harrison@...el.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220827002135.139349-1-umesh.nerlige.ramappa@intel.com
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
(cherry picked from commit 31335aa8e08be3fe10c50aecd2f11aba77544a78)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index 96022f49f9b5..d7e4681d7297 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1438,7 +1438,12 @@ void intel_guc_busyness_park(struct intel_gt *gt)
 	if (!guc_submission_initialized(guc))
 		return;
 
-	cancel_delayed_work(&guc->timestamp.work);
+	/*
+	 * There is a race with suspend flow where the worker runs after suspend
+	 * and causes an unclaimed register access warning. Cancel the worker
+	 * synchronously here.
+	 */
+	cancel_delayed_work_sync(&guc->timestamp.work);
 
 	/*
 	 * Before parking, we should sample engine busyness stats if we need to.
-- 
2.35.1