[PATCH 06/53] drm/i915/selftests: Allow for larger engine counts

[Lucas De Marchi]

On Thu, Jul 01, 2021 at 01:23:40PM -0700, Matt Roper wrote:
>From: John Harrison <John.C.Harrison at Intel.com>
>
>Increasing the engine count causes a couple of local array variables
>to exceed the kernel stack limit. So make them dynamic allocations
>instead.
>
>Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
>Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
>---
> drivers/gpu/drm/i915/gt/selftest_execlists.c  | 10 ++++--
> .../gpu/drm/i915/gt/selftest_workarounds.c    | 32 ++++++++++++-------
> 2 files changed, 29 insertions(+), 13 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/gt/selftest_execlists.c b/drivers/gpu/drm/i915/gt/selftest_execlists.c
>index 08896ae027d5..1e7fe2222479 100644
>--- a/drivers/gpu/drm/i915/gt/selftest_execlists.c
>+++ b/drivers/gpu/drm/i915/gt/selftest_execlists.c
>@@ -3561,12 +3561,16 @@ static int smoke_crescendo(struct preempt_smoke *smoke, unsigned int flags)
> #define BATCH BIT(0)
> {
> 	struct task_struct *tsk[I915_NUM_ENGINES] = {};
>-	struct preempt_smoke arg[I915_NUM_ENGINES];
>+	struct preempt_smoke *arg;
> 	struct intel_engine_cs *engine;
> 	enum intel_engine_id id;
> 	unsigned long count;
> 	int err = 0;
>
>+	arg = kmalloc_array(I915_NUM_ENGINES, sizeof(*arg), GFP_KERNEL);
>+	if (!arg)
>+		return -ENOMEM;
>+
> 	for_each_engine(engine, smoke->gt, id) {
> 		arg[id] = *smoke;
> 		arg[id].engine = engine;
>@@ -3574,7 +3578,7 @@ static int smoke_crescendo(struct preempt_smoke *smoke, unsigned int flags)
> 			arg[id].batch = NULL;
> 		arg[id].count = 0;
>
>-		tsk[id] = kthread_run(smoke_crescendo_thread, &arg,
>+		tsk[id] = kthread_run(smoke_crescendo_thread, arg,
> 				      "igt/smoke:%d", id);
> 		if (IS_ERR(tsk[id])) {
> 			err = PTR_ERR(tsk[id]);
>@@ -3603,6 +3607,8 @@ static int smoke_crescendo(struct preempt_smoke *smoke, unsigned int flags)
>
> 	pr_info("Submitted %lu crescendo:%x requests across %d engines and %d contexts\n",
> 		count, flags, smoke->gt->info.num_engines, smoke->ncontext);
>+
>+	kfree(arg);
> 	return 0;


this looks correctly, but apparently this test doesn't test anything as
`err` is write-only - there is only one read, but basically to avoid
overriding an earlier error.

looks like this should be `return err;` ?
+Chris

This patch itself looks good.

Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>

Lucas De Marchi