From: Sebastian Andrzej Siewior Date: Mon, 14 Jul 2025 15:39:48 +0000 (+0200) Subject: drm/i915: Don't check for atomic context on PREEMPT_RT X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=8a643df55f3a9c034cf8d1942c25a6eb08d57d9d;p=users%2Fwilly%2Fxarray.git drm/i915: Don't check for atomic context on PREEMPT_RT The !in_atomic() check in _wait_for_atomic() triggers on PREEMPT_RT because the uncore::lock is a spinlock_t and does not disable preemption or interrupts. Changing the uncore:lock to a raw_spinlock_t doubles the worst case latency on an otherwise idle testbox during testing. Ignore _WAIT_FOR_ATOMIC_CHECK() on PREEMPT_RT. Reviewed-by: Tvrtko Ursulin Link: https://lore.kernel.org/all/20211006164628.s2mtsdd2jdbfyf7g@linutronix.de/ Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20250714153954.629393-4-bigeasy@linutronix.de Signed-off-by: Maarten Lankhorst --- diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h index f7fb40cfdb70..9cb40c2c4b12 100644 --- a/drivers/gpu/drm/i915/i915_utils.h +++ b/drivers/gpu/drm/i915/i915_utils.h @@ -267,8 +267,13 @@ wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms) (Wmax)) #define wait_for(COND, MS) _wait_for((COND), (MS) * 1000, 10, 1000) -/* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */ -#if IS_ENABLED(CONFIG_DRM_I915_DEBUG) && IS_ENABLED(CONFIG_PREEMPT_COUNT) +/* + * If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. + * On PREEMPT_RT the context isn't becoming atomic because it is used in an + * interrupt handler or because a spinlock_t is acquired. This leads to + * warnings which don't occur otherwise and therefore the check is disabled. + */ +#if IS_ENABLED(CONFIG_DRM_I915_DEBUG) && IS_ENABLED(CONFIG_PREEMPT_COUNT) && !defined(CONFIG_PREEMPT_RT) # define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) WARN_ON_ONCE((ATOMIC) && !in_atomic()) #else # define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) do { } while (0)