/** * function ttm_eu_reserve_buffers * * @ticket: [out] ww_acquire_ctx filled in by call, or NULL if only * non-blocking reserves should be tried. * @list: thread private list of ttm_validate_buffer structs. * * Tries to reserve bos pointed to by the list entries for validation. * If the function returns 0, all buffers are marked as "unfenced", * taken off the lru lists and are not synced for write CPU usage. * * If the function detects a deadlock due to multiple threads trying to * reserve the same buffers in reverse order, all threads except one will * back off and retry. This function may sleep while waiting for * CPU write reservations to be cleared, and for other threads to * unreserve their buffers. * * This function may return -ERESTART or -EAGAIN if the calling process * receives a signal while waiting. In that case, no buffers on the list * will be reserved upon return. * * Buffers reserved by this function should be unreserved by * a call to either ttm_eu_backoff_reservation() or * ttm_eu_fence_buffer_objects() when command submission is complete or * has failed. */ /* * Reserve buffers for validation. * * If a buffer in the list is marked for CPU access, we back off and * wait for that buffer to become free for GPU access. * * If a buffer is reserved for another validation, the validator with * the highest validation sequence backs off and waits for that buffer * to become unreserved. This prevents deadlocks when validating multiple * buffers in different orders. */