On Tue, Jul 15, 2025 at 05:41:30PM +0200, Maarten Lankhorst wrote:
> From: Sebastian Andrzej Siewior <bige...@linutronix.de>
>
> Locking and/ or running inside interrupt handler will not lead to an
> atomic section on PREEMPT_RT. The RCU read section needs to be
> considered because all locks, which become sleeping locks on
> PREEMPT_RT, start a RCU read section. Scheduling/ sleeping while within
> a RCU read section is invalid.
>
> Check for also for RCU read section in stop_timeout() to determine if it
> is safe to sleep.
>
> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
> Link: https://lore.kernel.org/r/20250714153954.629393-9-bige...@linutronix.de
> Signed-off-by: Maarten Lankhorst <d...@lankhorst.se>
Reviewed-by: Rodrigo Vivi <rodrigo.v...@intel.com>
> ---
> drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> index b721bbd233567..f5a6143ea8a24 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> @@ -1609,7 +1609,7 @@ u64 intel_engine_get_last_batch_head(const struct
> intel_engine_cs *engine)
>
> static unsigned long stop_timeout(const struct intel_engine_cs *engine)
> {
> - if (in_atomic() || irqs_disabled()) /* inside atomic preempt-reset? */
> + if (in_atomic() || irqs_disabled() || rcu_preempt_depth()) /* inside
> atomic preempt-reset? */
> return 0;
>
> /*
> --
> 2.45.2
>
