From 23608382476c7bdfaa7489b1bc48f46c50506b85 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Tue, 3 Oct 2023 21:37:21 +0200 Subject: [PATCH 169/198] drm/i915/guc: Consider also RCU depth in busy loop. intel_guc_send_busy_loop() looks at in_atomic() and irqs_disabled() to decide if it should busy-spin while waiting or if it may sleep. Both checks will report false on PREEMPT_RT if sleeping spinlocks are acquired leading to RCU splats while the function sleeps. Check also if RCU has been disabled. Reported-by: "John B. Wyatt IV" Signed-off-by: Sebastian Andrzej Siewior --- drivers/gpu/drm/i915/gt/uc/intel_guc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h index 8dc291ff0093..5b8d084c9c58 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h @@ -317,7 +317,7 @@ static inline int intel_guc_send_busy_loop(struct intel_guc *guc, { int err; unsigned int sleep_period_ms = 1; - bool not_atomic = !in_atomic() && !irqs_disabled(); + bool not_atomic = !in_atomic() && !irqs_disabled() && !rcu_preempt_depth(); /* * FIXME: Have caller pass in if we are in an atomic context to avoid -- 2.44.0