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" <jwyatt@xxxxxxxxxx>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
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 57b9031327767..ff213b79ba83d 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
@@ -362,7 +362,7 @@ 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
--
2.45.2
