From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> To: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org Cc: David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, Jani Nikula <jani.nikula@linux.intel.com>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, Rodrigo Vivi <rodrigo.vivi@intel.com>, Chris Wilson <chris@chris-wilson.co.uk>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Clark Williams <williams@redhat.com>, Sebastian Andrzej Siewior <bigeasy@linutronix.de> Subject: [PATCH 1/2] drm/i915/gt: Queue and wait for the irq_work item. Date: Wed, 8 Sep 2021 20:57:02 +0200 [thread overview] Message-ID: <20210908185703.2989414-2-bigeasy@linutronix.de> (raw) In-Reply-To: <20210908185703.2989414-1-bigeasy@linutronix.de> Disabling interrupts and invoking the irq_work function directly breaks on PREEMPT_RT. PREEMPT_RT does not invoke all irq_work from hardirq context because some of the user have spinlock_t locking in the callback function. These locks are then turned into a sleeping locks which can not be acquired with disabled interrupts. Using irq_work_queue() has the benefit that the irqwork will be invoked in the regular context. In general there is "no" delay between enqueuing the callback and its invocation because the interrupt is raised right away on architectures which support it (which includes x86). Use irq_work_queue() + irq_work_sync() instead invoking the callback directly. Reported-by: Clark Williams <williams@redhat.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index 38cc42783dfb2..594dec2f76954 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -318,10 +318,9 @@ void __intel_breadcrumbs_park(struct intel_breadcrumbs *b) /* Kick the work once more to drain the signalers, and disarm the irq */ irq_work_sync(&b->irq_work); while (READ_ONCE(b->irq_armed) && !atomic_read(&b->active)) { - local_irq_disable(); - signal_irq_work(&b->irq_work); - local_irq_enable(); + irq_work_queue(&b->irq_work); cond_resched(); + irq_work_sync(&b->irq_work); } } -- 2.33.0
WARNING: multiple messages have this Message-ID (diff)
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> To: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org Cc: David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, Jani Nikula <jani.nikula@linux.intel.com>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, Rodrigo Vivi <rodrigo.vivi@intel.com>, Chris Wilson <chris@chris-wilson.co.uk>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Clark Williams <williams@redhat.com>, Sebastian Andrzej Siewior <bigeasy@linutronix.de> Subject: [Intel-gfx] [PATCH 1/2] drm/i915/gt: Queue and wait for the irq_work item. Date: Wed, 8 Sep 2021 20:57:02 +0200 [thread overview] Message-ID: <20210908185703.2989414-2-bigeasy@linutronix.de> (raw) In-Reply-To: <20210908185703.2989414-1-bigeasy@linutronix.de> Disabling interrupts and invoking the irq_work function directly breaks on PREEMPT_RT. PREEMPT_RT does not invoke all irq_work from hardirq context because some of the user have spinlock_t locking in the callback function. These locks are then turned into a sleeping locks which can not be acquired with disabled interrupts. Using irq_work_queue() has the benefit that the irqwork will be invoked in the regular context. In general there is "no" delay between enqueuing the callback and its invocation because the interrupt is raised right away on architectures which support it (which includes x86). Use irq_work_queue() + irq_work_sync() instead invoking the callback directly. Reported-by: Clark Williams <williams@redhat.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index 38cc42783dfb2..594dec2f76954 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -318,10 +318,9 @@ void __intel_breadcrumbs_park(struct intel_breadcrumbs *b) /* Kick the work once more to drain the signalers, and disarm the irq */ irq_work_sync(&b->irq_work); while (READ_ONCE(b->irq_armed) && !atomic_read(&b->active)) { - local_irq_disable(); - signal_irq_work(&b->irq_work); - local_irq_enable(); + irq_work_queue(&b->irq_work); cond_resched(); + irq_work_sync(&b->irq_work); } } -- 2.33.0
next prev parent reply other threads:[~2021-09-08 19:05 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-08 18:57 [PATCH 0/2] drm/i915/gt: Locking splats PREEMPT_RT Sebastian Andrzej Siewior 2021-09-08 18:57 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-09-08 18:57 ` Sebastian Andrzej Siewior [this message] 2021-09-08 18:57 ` [Intel-gfx] [PATCH 1/2] drm/i915/gt: Queue and wait for the irq_work item Sebastian Andrzej Siewior 2021-09-08 18:57 ` [RFC PATCH 2/2] drm/i915/gt: Use spin_lock_irq() instead of local_irq_disable() + spin_lock() Sebastian Andrzej Siewior 2021-09-08 18:57 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-09-16 9:38 ` Maarten Lankhorst 2021-10-01 9:29 ` Sebastian Andrzej Siewior 2021-09-08 19:25 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for drm/i915/gt: Locking splats PREEMPT_RT Patchwork 2022-03-11 12:30 [PATCH 0/2] drm/i915: Avoid explicit IRQ-off sections Sebastian Andrzej Siewior 2022-03-11 12:30 ` [PATCH 1/2] drm/i915/gt: Queue and wait for the irq_work item Sebastian Andrzej Siewior
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