drm/i915: Perform a direct reset of the GPU from the waiter
If a waiter is holding the struct_mutex, then the reset worker cannot
reset the GPU until the waiter returns. We do not want to return -EAGAIN
form i915_wait_request as that breaks delicate operations like
i915_vma_unbind() which often cannot be restarted easily, and returning
-EIO is just as useless (and has in the past proven dangerous). The
remaining WARN_ON(i915_wait_request) serve as a valuable reminder that
handling errors from an indefinite wait are tricky.
We can keep the current semantic that knowing after a reset is complete,
so is the request, by performing the reset ourselves if we hold the
mutex.
uevent emission is still handled by the reset worker, so it may appear
slightly out of order with respect to the actual reset (and concurrent
use of the device).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160909131201.16673-11-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 20b7743..15f1977 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3863,7 +3863,9 @@
schedule_timeout_uninterruptible(remaining_jiffies);
}
}
-static inline bool __i915_request_irq_complete(struct drm_i915_gem_request *req)
+
+static inline bool
+__i915_request_irq_complete(struct drm_i915_gem_request *req)
{
struct intel_engine_cs *engine = req->engine;
@@ -3925,17 +3927,6 @@
return true;
}
- /* We need to check whether any gpu reset happened in between
- * the request being submitted and now. If a reset has occurred,
- * the seqno will have been advance past ours and our request
- * is complete. If we are in the process of handling a reset,
- * the request is effectively complete as the rendering will
- * be discarded, but we need to return in order to drop the
- * struct_mutex.
- */
- if (i915_reset_in_progress(&req->i915->gpu_error))
- return true;
-
return false;
}