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Chris Wilson authored
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
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