[Intel-gfx] [PATCH 4/6] drm/i915: fix reset handling in the throttle ioctl

[Daniel Vetter]

While auditing the code I've noticed one place (the throttle ioctl)
which does not yet wait for the reset handler to complete and doesn't
properly decode the wedge state into -EAGAIN/-EIO. Fix this up by
calling the right helpers. This might explain the oddball "my
compositor just died in a successfull gpu reset" reports. Or maybe not, since
current mesa doesn't use this ioctl to throttle command submission.

The throttle ioctl doesn't take the struct_mutex, so to avoid busy-looping
with -EAGAIN while a reset is in process, check for errors first and wait
for the handler to complete if a reset is pending by calling
i915_gem_wait_for_error.

Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/i915_gem.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b2620c7..55cdad9 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3402,8 +3402,13 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
 	u32 seqno = 0;
 	int ret;
 
-	if (atomic_read(&dev_priv->gpu_error.wedged))
-		return -EIO;
+	ret = i915_gem_wait_for_error(&dev_priv->gpu_error);
+	if (ret)
+		return ret;
+
+	ret = i915_gem_check_wedge(&dev_priv->gpu_error, false);
+	if (ret)
+		return ret;
 
 	spin_lock(&file_priv->mm.lock);
 	list_for_each_entry(request, &file_priv->mm.request_list, client_list) {
-- 
1.7.11.4