From 1dfffa0051eae890ce36924651ecff60df5d779e Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 17 Oct 2019 18:13:52 +0200 Subject: [PATCH] drm/i915: Don't disable interrupts independently of the lock The locks (active.lock and rq->lock) need to be taken with disabled interrupts. This is done in i915_request_retire() by disabling the interrupts independently of the locks itself. While local_irq_disable()+spin_lock() equals spin_lock_irq() on vanilla it does not on PREEMPT_RT. Chris Wilson confirmed that local_irq_disable() was just introduced as an optimisation to avoid enabling/disabling interrupts during lock/unlock combo. Enable/disable interrupts as part of the locking instruction. Cc: Chris Wilson Reviewed-by: Chris Wilson Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Chris Wilson Link: https://patchwork.freedesktop.org/patch/msgid/20191017161352.e5z3ugse7gxl5ari@linutronix.de --- drivers/gpu/drm/i915/i915_request.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index f1cadad4e81c..4575f368455d 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -206,14 +206,14 @@ static void remove_from_engine(struct i915_request *rq) * check that the rq still belongs to the newly locked engine. */ locked = READ_ONCE(rq->engine); - spin_lock(&locked->active.lock); + spin_lock_irq(&locked->active.lock); while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) { spin_unlock(&locked->active.lock); spin_lock(&engine->active.lock); locked = engine; } list_del(&rq->sched.link); - spin_unlock(&locked->active.lock); + spin_unlock_irq(&locked->active.lock); } bool i915_request_retire(struct i915_request *rq) @@ -242,8 +242,6 @@ bool i915_request_retire(struct i915_request *rq) &i915_request_timeline(rq)->requests)); rq->ring->head = rq->postfix; - local_irq_disable(); - /* * We only loosely track inflight requests across preemption, * and so we may find ourselves attempting to retire a _completed_ @@ -252,7 +250,7 @@ bool i915_request_retire(struct i915_request *rq) */ remove_from_engine(rq); - spin_lock(&rq->lock); + spin_lock_irq(&rq->lock); i915_request_mark_complete(rq); if (!i915_request_signaled(rq)) dma_fence_signal_locked(&rq->fence); @@ -267,9 +265,7 @@ bool i915_request_retire(struct i915_request *rq) __notify_execute_cb(rq); } GEM_BUG_ON(!list_empty(&rq->execute_cb)); - spin_unlock(&rq->lock); - - local_irq_enable(); + spin_unlock_irq(&rq->lock); remove_from_client(rq); list_del(&rq->link); -- 2.30.2