linux-kernel - [PATCH] drm/i915/gt: Handle INTEL_WAKEREF_DEF return value in gen8_ggtt_bind_get

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Message-Id: <20250116193528.2297487-1-ingyujang25@gmail.com>
Date: Fri, 17 Jan 2025 04:35:28 +0900
From: Ingyu Jang <ingyujang25@...il.com>
To: Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>
Cc: Ingyu Jang <ingyujang25@...il.com>,
	intel-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] drm/i915/gt: Handle INTEL_WAKEREF_DEF return value in gen8_ggtt_bind_get_ce

The function 'gen8_ggtt_bind_get_ce' previously did not handle the case
where 'intel_gt_pm_get_if_awake()' returns 'INTEL_WAKEREF_DEF'.
This value is returned when the 'intel_ref_tracker_alloc()' call within
'intel_gt_pm_get_if_awake()' fails to allocate due
to memory pressure or other constraints.

'intel_ref_tracker_alloc()' uses 'ref_tracker_alloc()' with the
'GFP_NOWAIT' flag, which can return 'NULL' if allocation fails.
In this case, the function explicitly returns 'INTEL_WAKEREF_DEF'.

This patch adds a check for 'INTEL_WAKEREF_DEF' in
'gen8_ggtt_bind_get_ce' to ensure that such errors are properly handled.
If 'INTEL_WAKEREF_DEF' is returned, the function returns 'NULL' .

Signed-off-by: Ingyu Jang <ingyujang25@...il.com>
---
 drivers/gpu/drm/i915/gt/intel_ggtt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
index d60a6ca0cae5..8d22d8f2243d 100644
--- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
+++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
@@ -311,7 +311,7 @@ static struct intel_context *gen8_ggtt_bind_get_ce(struct i915_ggtt *ggtt, intel
 	 * doing rpm_resume().
 	 */
 	*wakeref = intel_gt_pm_get_if_awake(gt);
-	if (!*wakeref)
+	if (!*wakeref || *wakeref == INTEL_WAKEREF_DEF)
 		return NULL;

 	intel_engine_pm_get(ce->engine);
-- 
2.34.1