| Message ID | 20240405142737.920626-10-bigeasy@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915: PREEMPT_RT related fixups. | expand |
On Fri, Apr 05, 2024 at 04:18:27PM +0200, Sebastian Andrzej Siewior wrote: > 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@redhat.com> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> > --- > 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 be70c46604b49..387cc1911302f 100644 > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h > @@ -360,7 +360,7 @@ 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 > -- > 2.43.0 >
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h index be70c46604b49..387cc1911302f 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h @@ -360,7 +360,7 @@ 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
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@redhat.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/gpu/drm/i915/gt/uc/intel_guc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)