"ring->space" is unsigned so it's never less than zero.
Signed-off-by: Dan Carpenter error27@gmail.com
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 51e9c9e..a331898 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -208,9 +208,10 @@ static int init_ring_common(struct drm_device *dev, else { ring->head = ring->get_head(dev, ring); ring->tail = ring->get_tail(dev, ring); - ring->space = ring->head - (ring->tail + 8); - if (ring->space < 0) - ring->space += ring->size; + if (ring->head >= ring->tail + 8) + ring->space = ring->head - (ring->tail + 8); + else + ring->space = ring->head - (ring->tail + 8) + ring->size; } return 0; } @@ -666,9 +667,10 @@ int intel_init_ring_buffer(struct drm_device *dev, else { ring->head = ring->get_head(dev, ring); ring->tail = ring->get_tail(dev, ring); - ring->space = ring->head - (ring->tail + 8); - if (ring->space < 0) - ring->space += ring->size; + if (ring->head >= ring->tail + 8) + ring->space = ring->head - (ring->tail + 8); + else + ring->space = ring->head - (ring->tail + 8) + ring->size; } INIT_LIST_HEAD(&ring->active_list); INIT_LIST_HEAD(&ring->request_list); @@ -735,9 +737,10 @@ int intel_wait_ring_buffer(struct drm_device *dev, end = jiffies + 3 * HZ; do { ring->head = ring->get_head(dev, ring); - ring->space = ring->head - (ring->tail + 8); - if (ring->space < 0) - ring->space += ring->size; + if (ring->head >= ring->tail + 8) + ring->space = ring->head - (ring->tail + 8); + else + ring->space = ring->head - (ring->tail + 8) + ring->size; if (ring->space >= n) { trace_i915_ring_wait_end (dev); return 0; diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c index 44af317..707f32f 100644 --- a/drivers/gpu/drm/i915/i915_dma.c +++ b/drivers/gpu/drm/i915/i915_dma.c @@ -109,9 +109,10 @@ void i915_kernel_lost_context(struct drm_device * dev)
ring->head = I915_READ(PRB0_HEAD) & HEAD_ADDR; ring->tail = I915_READ(PRB0_TAIL) & TAIL_ADDR; - ring->space = ring->head - (ring->tail + 8); - if (ring->space < 0) - ring->space += ring->size; + if (ring->head >= ring->tail + 8) + ring->space = ring->head - (ring->tail + 8); + else + ring->space = ring->head - (ring->tail + 8) + ring->size;
if (!dev->primary->master) return;