[PATCH V3 5/6] drm/i915: Update the restrict check to filter out wrong Ring ID passed by user-space

[Zhao Yakui <yakui.zhao@intel.com>]

One extra ring is added in the kernel driver but it is transparent to the
user-space application/middleware. In such case the number of the rings
in kernel driver is bigger than that exported to the user-space. So
it needs to filter out the wrong Ring ID passed by user-space.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |    2 +-
 drivers/gpu/drm/i915/intel_ringbuffer.h    |    1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 3491402..341ec68 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1035,7 +1035,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 	if (args->flags & I915_EXEC_IS_PINNED)
 		flags |= I915_DISPATCH_PINNED;
 
-	if ((args->flags & I915_EXEC_RING_MASK) > I915_NUM_RINGS) {
+	if ((args->flags & I915_EXEC_RING_MASK) > LAST_USER_RING) {
 		DRM_DEBUG("execbuf with unknown ring: %d\n",
 			  (int)(args->flags & I915_EXEC_RING_MASK));
 		return -EINVAL;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 8ca4285..59f4cdd 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -64,6 +64,7 @@ struct  intel_ring_buffer {
 		VCS2,
 	} id;
 #define I915_NUM_RINGS 5
+#define LAST_USER_RING (VECS + 1)
 	u32		mmio_base;
 	void		__iomem *virtual_start;
 	struct		drm_device *dev;
-- 
1.7.10.1