2019-05-29 19:49:30 +00:00
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Wed, 10 Apr 2019 11:01:37 +0200
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2019-11-25 00:04:39 +00:00
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Subject: [PATCH 266/290] drm/i915: Don't disable interrupts independently of
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2019-05-29 19:49:30 +00:00
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the lock
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2019-11-25 00:04:39 +00:00
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Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=1fd04accf7d1da34be2d03a8cc9db0ba68c8cf9f
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2019-05-29 19:49:30 +00:00
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The locks (timeline->lock and rq->lock) need to be taken with disabled
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interrupts. This is done in __retire_engine_request() by disabling the
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interrupts independently of the locks itself.
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While local_irq_disable()+spin_lock() equals spin_lock_irq() on vanilla
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it does not on RT. Also, it is not obvious if there is a special reason
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to why the interrupts are disabled independently of the lock.
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Enable/disable interrupts as part of the locking instruction.
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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---
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drivers/gpu/drm/i915/i915_request.c | 8 ++------
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1 file changed, 2 insertions(+), 6 deletions(-)
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diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
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index 5c2c93cbab12..7124510b9131 100644
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--- a/drivers/gpu/drm/i915/i915_request.c
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+++ b/drivers/gpu/drm/i915/i915_request.c
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@@ -356,9 +356,7 @@ static void __retire_engine_request(struct intel_engine_cs *engine,
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GEM_BUG_ON(!i915_request_completed(rq));
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- local_irq_disable();
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-
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- spin_lock(&engine->timeline.lock);
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+ spin_lock_irq(&engine->timeline.lock);
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GEM_BUG_ON(!list_is_first(&rq->link, &engine->timeline.requests));
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list_del_init(&rq->link);
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spin_unlock(&engine->timeline.lock);
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@@ -372,9 +370,7 @@ static void __retire_engine_request(struct intel_engine_cs *engine,
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GEM_BUG_ON(!atomic_read(&rq->i915->gt_pm.rps.num_waiters));
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atomic_dec(&rq->i915->gt_pm.rps.num_waiters);
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}
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- spin_unlock(&rq->lock);
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-
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- local_irq_enable();
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+ spin_unlock_irq(&rq->lock);
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/*
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* The backing object for the context is done after switching to the
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