drm/msm: return -EBUSY if bo still active

When we CPU_PREP a bo with NOSYNC flag (for example, to implement
PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE), an -EBUSY return indicates to
userspace that the bo is still busy.  Previously it was incorrectly
returning 0 in this case.

And while we're in there throw in an bit of extra sanity checking in
case userspace tries to wait for a bogus fence.
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/msm_drv.c

@@ -499,10 +499,24 @@ int msm_wait_fence_interruptable(struct drm_device *dev, uint32_t fence,
 		struct timespec *timeout)
 {
 	struct msm_drm_private *priv = dev->dev_private;
+	int ret;
+
+	if (!priv->gpu)
+		return 0;
+
+	if (fence > priv->gpu->submitted_fence) {
+		DRM_ERROR("waiting on invalid fence: %u (of %u)\n",
+				fence, priv->gpu->submitted_fence);
+		return -EINVAL;
+	}
+
+	if (!timeout) {
+		/* no-wait: */
+		ret = fence_completed(dev, fence) ? 0 : -EBUSY;
+	} else {
 		unsigned long timeout_jiffies = timespec_to_jiffies(timeout);
 		unsigned long start_jiffies = jiffies;
 		unsigned long remaining_jiffies;
-	int ret;
 
 		if (time_after(start_jiffies, timeout_jiffies))
 			remaining_jiffies = 0;
@@ -510,8 +524,9 @@ int msm_wait_fence_interruptable(struct drm_device *dev, uint32_t fence,
 			remaining_jiffies = timeout_jiffies - start_jiffies;
 
 		ret = wait_event_interruptible_timeout(priv->fence_event,
-			priv->completed_fence >= fence,
+				fence_completed(dev, fence),
 				remaining_jiffies);
+
 		if (ret == 0) {
 			DBG("timeout waiting for fence: %u (completed: %u)",
 					fence, priv->completed_fence);
@@ -519,6 +534,7 @@ int msm_wait_fence_interruptable(struct drm_device *dev, uint32_t fence,
 		} else if (ret != -ERESTARTSYS) {
 			ret = 0;
 		}
+	}
 
 	return ret;
 }

drivers/gpu/drm/msm/msm_drv.h

@@ -191,6 +191,12 @@ u32 msm_readl(const void __iomem *addr);
 #define DBG(fmt, ...) DRM_DEBUG(fmt"\n", ##__VA_ARGS__)
 #define VERB(fmt, ...) if (0) DRM_DEBUG(fmt"\n", ##__VA_ARGS__)
 
+static inline bool fence_completed(struct drm_device *dev, uint32_t fence)
+{
+	struct msm_drm_private *priv = dev->dev_private;
+	return priv->completed_fence >= fence;
+}
+
 static inline int align_pitch(int width, int bpp)
 {
 	int bytespp = (bpp + 7) / 8;

drivers/gpu/drm/msm/msm_gem.c

@@ -437,12 +437,16 @@ int msm_gem_cpu_prep(struct drm_gem_object *obj, uint32_t op,
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
 	int ret = 0;
 
-	if (is_active(msm_obj) && !(op & MSM_PREP_NOSYNC)) {
+	if (is_active(msm_obj)) {
 		uint32_t fence = 0;
+
 		if (op & MSM_PREP_READ)
 			fence = msm_obj->write_fence;
 		if (op & MSM_PREP_WRITE)
 			fence = max(fence, msm_obj->read_fence);
+		if (op & MSM_PREP_NOSYNC)
+			timeout = NULL;
+
 		ret = msm_wait_fence_interruptable(dev, fence, timeout);
 	}