[PATCH 0/2] Updates to fence api

The following series implements small updates to the fence api. I've found them useful when implementing the fence API in ttm and i915.

The last patch enables RCU on top of the api. I've found this less useful, but it was the condition on which Thomas Hellstrom was ok with converting TTM to fence, so I had to keep it in.

If nobody objects I'll probably merge that patch through drm, because some care is needed in ttm before it can flip the switch on rcu.

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Maarten Lankhorst (2): reservation: update api and add some helpers [RFC] reservation: add suppport for read-only access using rcu