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. Therefore I'm currently unsure about changing this.
Link: https://lore.kernel.org/all/20211006164628.s2mtsdd2jdbfyf7g@linutronix.de/ Signed-off-by: Sebastian Andrzej Siewior bigeasy@linutronix.de --- drivers/gpu/drm/i915/i915_utils.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h index 7a5925072466a..b7b56fb1e2fc7 100644 --- a/drivers/gpu/drm/i915/i915_utils.h +++ b/drivers/gpu/drm/i915/i915_utils.h @@ -344,7 +344,7 @@ wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms) #define wait_for(COND, MS) _wait_for((COND), (MS) * 1000, 10, 1000)
/* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */ -#if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT) +#if defined(CONFIG_DRM_I915_DEBUG) && defined(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)