From e5330ac1f50b897d245753828e8887f297f69dd0 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 31 Oct 2017 12:22:35 +0000
Subject: [PATCH] drm/i915: Check that the breadcrumb wasn't disarmed automatically before parking
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Git-commit: e5330ac1f50b897d245753828e8887f297f69dd0
Patch-mainline: v4.16-rc1
References: FATE#322643 bsc#1055900

We will disarm the breadcrumb interrupt if we see a user interrupt
whilst no one is waiting. This may race with the call to
intel_engine_disarm_breadcrumbs() triggering an assert that we aren't
trying to do the same job twice. Prevent this by checking that the irq
is still armed after flushing the interrupt (for the irq spinlock).

Fixes: bcbd5c33a342 ("drm/i915/guc: Always enable the breadcrumbs irq")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171031122235.1395-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/intel_breadcrumbs.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -219,7 +219,8 @@ void intel_engine_disarm_breadcrumbs(str
 
 	spin_lock(&b->irq_lock);
 	first = fetch_and_zero(&b->irq_wait);
-	__intel_engine_disarm_breadcrumbs(engine);
+	if (b->irq_armed)
+		__intel_engine_disarm_breadcrumbs(engine);
 	spin_unlock(&b->irq_lock);
 
 	rbtree_postorder_for_each_entry_safe(wait, n, &b->waiters, node) {