[Intel-gfx] [PATCH 3/3] drm/i915: Assert the csb tail is within bounds

[Mika Kuoppala]

Make sure that the tail we get from hardware fits
within the bounds dictated by our count of csb entries.

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 107244ab09ef..1a34e91c1305 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -888,6 +888,7 @@ static void process_csb(struct intel_engine_cs *engine)
 	 */
 	head = execlists->csb_head;
 	tail = READ_ONCE(*execlists->csb_write);
+	GEM_DEBUG_BUG_ON(tail >= execlists->csb_entries);
 	GEM_TRACE("%s cs-irq head=%d, tail=%d\n", engine->name, head, tail);
 	if (unlikely(head == tail))
 		return;
-- 
2.17.1