From f3ef0233b3a48ebffc03fee9ad48571d05159826 Mon Sep 17 00:00:00 2001
From: John Harrison <John.C.Harrison@Intel.com>
Date: Thu, 5 May 2022 14:38:06 -0700
Subject: drm/i915/pvc: Reduce stack usage in reset selftest with extra blitter
 engine
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Git-commit: 6cd96877c7da6bc3a28ef0bcb3bc7470f4dd9aa6
Patch-mainline: v6.0-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 jsc#PED-2849

PVC adds extra blitter engines (in the following patch). The reset
selftest has a local array on the stack which is sized by the number
of engines. The increase pushes the size of this array to the point
where it trips the 'stack too large' compile warning. This patch takes
the allocation of the stack and makes it dynamic instead.

v2 (MattR):
 - Minor cosmetic changes:  re-sort definition and allocate using
   kmalloc_array().  (Tvrtko)

Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220505213812.3979301-7-matthew.d.roper@intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/gt/selftest_hangcheck.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
index 83ff4c2e57c5..6493265d5f64 100644
--- a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
+++ b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
@@ -976,6 +976,7 @@ static int __igt_reset_engines(struct intel_gt *gt,
 {
 	struct i915_gpu_error *global = &gt->i915->gpu_error;
 	struct intel_engine_cs *engine, *other;
+	struct active_engine *threads;
 	enum intel_engine_id id, tmp;
 	struct hang h;
 	int err = 0;
@@ -996,8 +997,11 @@ static int __igt_reset_engines(struct intel_gt *gt,
 			h.ctx->sched.priority = 1024;
 	}
 
+	threads = kmalloc_array(I915_NUM_ENGINES, sizeof(*threads), GFP_KERNEL);
+	if (!threads)
+		return -ENOMEM;
+
 	for_each_engine(engine, gt, id) {
-		struct active_engine threads[I915_NUM_ENGINES] = {};
 		unsigned long device = i915_reset_count(global);
 		unsigned long count = 0, reported;
 		bool using_guc = intel_engine_uses_guc(engine);
@@ -1016,7 +1020,7 @@ static int __igt_reset_engines(struct intel_gt *gt,
 			break;
 		}
 
-		memset(threads, 0, sizeof(threads));
+		memset(threads, 0, sizeof(*threads) * I915_NUM_ENGINES);
 		for_each_engine(other, gt, tmp) {
 			struct task_struct *tsk;
 
@@ -1236,6 +1240,7 @@ static int __igt_reset_engines(struct intel_gt *gt,
 			break;
 		}
 	}
+	kfree(threads);
 
 	if (intel_gt_is_wedged(gt))
 		err = -EIO;
-- 
2.38.1