diff options
Diffstat (limited to 'debian/patches-rt/drm-i915-Don-t-disable-interrupts-independently-of-t.patch')
| -rw-r--r-- | debian/patches-rt/drm-i915-Don-t-disable-interrupts-independently-of-t.patch | 65 |
1 files changed, 46 insertions, 19 deletions
diff --git a/debian/patches-rt/drm-i915-Don-t-disable-interrupts-independently-of-t.patch b/debian/patches-rt/drm-i915-Don-t-disable-interrupts-independently-of-t.patch index d03217e4d..c61307a9f 100644 --- a/debian/patches-rt/drm-i915-Don-t-disable-interrupts-independently-of-t.patch +++ b/debian/patches-rt/drm-i915-Don-t-disable-interrupts-independently-of-t.patch @@ -2,43 +2,70 @@ From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Wed, 10 Apr 2019 11:01:37 +0200 Subject: [PATCH] drm/i915: Don't disable interrupts independently of the lock -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.17-rt9.tar.xz +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patches-5.4.3-rt1.tar.xz -The locks (timeline->lock and rq->lock) need to be taken with disabled -interrupts. This is done in __retire_engine_request() by disabling the +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 RT. Also, it is not obvious if there is a special reason -to why the interrupts are disabled independently of the lock. +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 <chris@chris-wilson.co.uk> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- - drivers/gpu/drm/i915/i915_request.c | 8 ++------ - 1 file changed, 2 insertions(+), 6 deletions(-) + drivers/gpu/drm/i915/i915_request.c | 12 ++++-------- + 1 file changed, 4 insertions(+), 8 deletions(-) --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c -@@ -202,9 +202,7 @@ static void __retire_engine_request(stru +@@ -205,14 +205,14 @@ static void remove_from_engine(struct i9 + * 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); + } - GEM_BUG_ON(!i915_request_completed(rq)); + static bool i915_request_retire(struct i915_request *rq) +@@ -272,8 +272,6 @@ static bool i915_request_retire(struct i + active->retire(active, rq); + } - local_irq_disable(); - -- spin_lock(&engine->timeline.lock); -+ spin_lock_irq(&engine->timeline.lock); - GEM_BUG_ON(!list_is_first(&rq->link, &engine->timeline.requests)); - list_del_init(&rq->link); - spin_unlock(&engine->timeline.lock); -@@ -219,9 +217,7 @@ static void __retire_engine_request(stru - GEM_BUG_ON(!atomic_read(&rq->i915->gt_pm.rps.num_waiters)); - atomic_dec(&rq->i915->gt_pm.rps.num_waiters); + /* + * We only loosely track inflight requests across preemption, + * and so we may find ourselves attempting to retire a _completed_ +@@ -282,7 +280,7 @@ static bool i915_request_retire(struct i + */ + 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); +@@ -297,9 +295,7 @@ static bool i915_request_retire(struct i + __notify_execute_cb(rq); } + GEM_BUG_ON(!list_empty(&rq->execute_cb)); - spin_unlock(&rq->lock); - - local_irq_enable(); + spin_unlock_irq(&rq->lock); - /* - * The backing object for the context is done after switching to the + remove_from_client(rq); + list_del(&rq->link); |