[PATCH 4/4] drm/i915: don't hange userspace when the gpu reset is stuck

Daniel Vetter
2012-06-26T21:09:08Z

With the gpu reset no longer using a trylock we've the chances of
userspace getting stuck quite a bit. To make that (hopefully) rare
case more paletable time out when waiting for the gpu reset code to
complete and signal this little issue to the caller by returning -EIO.

This should help userspace to somewhat gracefully fall back and
hopefully allow the user to grab some logs and reboot the machine
(instead of staring at a frozen X screen in agony).

Suggested by Chris Wilson because I've been stubborn about allowing
the gpu reset code to fail.

Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/gpu/drm/i915/i915_gem.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index af6a510..7d28555 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -96,9 +96,18 @@ i915_gem_wait_for_error(struct drm_device *dev)
if (!atomic_read(&dev_priv->mm.wedged))
return 0;

- ret = wait_for_completion_interruptible(x);
- if (ret)
+ /*
+ * Only wait 10 seconds for the gpu reset to complete to avoid hanging
+ * userspace. If it takes that long something really bad is going on and
+ * we should simply try to bail out and fail as gracefully as possible.
+ */
+ ret = wait_for_completion_interruptible_timeout(x, 10*HZ);
+ if (ret == 0) {
+ DRM_ERROR("Timed out waiting for the gpu reset to complete\n");
+ return -EIO;
+ } else if (ret < 0) {
return ret;
+ }

if (atomic_read(&dev_priv->mm.wedged)) {
/* GPU is hung, bump the completion count to account for
--
1.7.10