diff options
Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0009-drm-i915-gt-Use-spin_lock_irq-instead-of-local_irq_d.patch | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/debian/patches-rt/0009-drm-i915-gt-Use-spin_lock_irq-instead-of-local_irq_d.patch b/debian/patches-rt/0009-drm-i915-gt-Use-spin_lock_irq-instead-of-local_irq_d.patch new file mode 100644 index 000000000..3245e145f --- /dev/null +++ b/debian/patches-rt/0009-drm-i915-gt-Use-spin_lock_irq-instead-of-local_irq_d.patch @@ -0,0 +1,89 @@ +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Wed, 8 Sep 2021 19:03:41 +0200 +Subject: [PATCH 09/10] drm/i915/gt: Use spin_lock_irq() instead of + local_irq_disable() + spin_lock() +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz + +execlists_dequeue() is invoked from a function which uses +local_irq_disable() to disable interrupts so the spin_lock() behaves +like spin_lock_irq(). +This breaks PREEMPT_RT because local_irq_disable() + spin_lock() is not +the same as spin_lock_irq(). + +execlists_dequeue_irq() and execlists_dequeue() has each one caller +only. If intel_engine_cs::active::lock is acquired and released with the +_irq suffix then it behaves almost as if execlists_dequeue() would be +invoked with disabled interrupts. The difference is the last part of the +function which is then invoked with enabled interrupts. +I can't tell if this makes a difference. From looking at it, it might +work to move the last unlock at the end of the function as I didn't find +anything that would acquire the lock again. + +Reported-by: Clark Williams <williams@redhat.com> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> +--- + drivers/gpu/drm/i915/gt/intel_execlists_submission.c | 17 +++++------------ + 1 file changed, 5 insertions(+), 12 deletions(-) + +--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c ++++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c +@@ -1303,7 +1303,7 @@ static void execlists_dequeue(struct int + * and context switches) submission. + */ + +- spin_lock(&sched_engine->lock); ++ spin_lock_irq(&sched_engine->lock); + + /* + * If the queue is higher priority than the last +@@ -1403,7 +1403,7 @@ static void execlists_dequeue(struct int + * Even if ELSP[1] is occupied and not worthy + * of timeslices, our queue might be. + */ +- spin_unlock(&sched_engine->lock); ++ spin_unlock_irq(&sched_engine->lock); + return; + } + } +@@ -1429,7 +1429,7 @@ static void execlists_dequeue(struct int + + if (last && !can_merge_rq(last, rq)) { + spin_unlock(&ve->base.sched_engine->lock); +- spin_unlock(&engine->sched_engine->lock); ++ spin_unlock_irq(&engine->sched_engine->lock); + return; /* leave this for another sibling */ + } + +@@ -1591,7 +1591,7 @@ static void execlists_dequeue(struct int + */ + sched_engine->queue_priority_hint = queue_prio(sched_engine); + i915_sched_engine_reset_on_empty(sched_engine); +- spin_unlock(&sched_engine->lock); ++ spin_unlock_irq(&sched_engine->lock); + + /* + * We can skip poking the HW if we ended up with exactly the same set +@@ -1617,13 +1617,6 @@ static void execlists_dequeue(struct int + } + } + +-static void execlists_dequeue_irq(struct intel_engine_cs *engine) +-{ +- local_irq_disable(); /* Suspend interrupts across request submission */ +- execlists_dequeue(engine); +- local_irq_enable(); /* flush irq_work (e.g. breadcrumb enabling) */ +-} +- + static void clear_ports(struct i915_request **ports, int count) + { + memset_p((void **)ports, NULL, count); +@@ -2478,7 +2471,7 @@ static void execlists_submission_tasklet + } + + if (!engine->execlists.pending[0]) { +- execlists_dequeue_irq(engine); ++ execlists_dequeue(engine); + start_timeslice(engine); + } + |