[PATCH 1/2] drm/i915/guc: Use correct lock when checking for stale CTB messages

[Michal Wajdeczko]

Access to CTB_RECV buffer descriptor is implicitly guarded
by gt->irq_lock, not i915->irq_lock. Use correct lock when
checking for stale messages outside irq handler.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 2 ++
 drivers/gpu/drm/i915/gt/uc/intel_uc.c     | 7 ++++---
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
index 11742fca0e9e..6b0768800fee 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
@@ -597,6 +597,8 @@ static int ct_read(struct intel_guc_ct *ct, u32 *data)
 	unsigned int len;
 	unsigned int i;
 
+	lockdep_assert_held(&ct_to_gt(ct)->irq_lock);
+
 	if (unlikely(desc->is_in_error))
 		return -EPIPE;
 
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
index affc4d6f9ead..375ff7347800 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
@@ -200,7 +200,8 @@ static void guc_disable_interrupts(struct intel_guc *guc)
 
 static int guc_enable_communication(struct intel_guc *guc)
 {
-	struct drm_i915_private *i915 = guc_to_gt(guc)->i915;
+	struct intel_gt *gt = guc_to_gt(guc);
+	struct drm_i915_private *i915 = gt->i915;
 	int ret;
 
 	GEM_BUG_ON(guc_communication_enabled(guc));
@@ -220,9 +221,9 @@ static int guc_enable_communication(struct intel_guc *guc)
 	guc_enable_interrupts(guc);
 
 	/* check for CT messages received before we enabled interrupts */
-	spin_lock_irq(&i915->irq_lock);
+	spin_lock_irq(&gt->irq_lock);
 	intel_guc_ct_event_handler(&guc->ct);
-	spin_unlock_irq(&i915->irq_lock);
+	spin_unlock_irq(&gt->irq_lock);
 
 	DRM_INFO("GuC communication enabled\n");
 
-- 
2.19.2