drm/ttm: add ttm_bo_reserve_slowpath
Instead of dropping everything, waiting for the bo to be unreserved and trying over, a better strategy would be to do a blocking wait. This can be mapped a lot better to a mutex_lock-like call. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Reviewed-by: Jerome Glisse <jglisse@redhat.com>
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@ -310,6 +310,53 @@ int ttm_bo_reserve(struct ttm_buffer_object *bo,
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return ret;
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}
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int ttm_bo_reserve_slowpath_nolru(struct ttm_buffer_object *bo,
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bool interruptible, uint32_t sequence)
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{
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bool wake_up = false;
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int ret;
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while (unlikely(atomic_xchg(&bo->reserved, 1) != 0)) {
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WARN_ON(bo->seq_valid && sequence == bo->val_seq);
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ret = ttm_bo_wait_unreserved(bo, interruptible);
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if (unlikely(ret))
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return ret;
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}
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if ((bo->val_seq - sequence < (1 << 31)) || !bo->seq_valid)
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wake_up = true;
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/**
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* Wake up waiters that may need to recheck for deadlock,
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* if we decreased the sequence number.
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*/
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bo->val_seq = sequence;
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bo->seq_valid = true;
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if (wake_up)
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wake_up_all(&bo->event_queue);
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return 0;
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}
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int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,
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bool interruptible, uint32_t sequence)
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{
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struct ttm_bo_global *glob = bo->glob;
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int put_count, ret;
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ret = ttm_bo_reserve_slowpath_nolru(bo, interruptible, sequence);
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if (likely(!ret)) {
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spin_lock(&glob->lru_lock);
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put_count = ttm_bo_del_from_lru(bo);
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spin_unlock(&glob->lru_lock);
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ttm_bo_list_ref_sub(bo, put_count, true);
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}
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return ret;
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}
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EXPORT_SYMBOL(ttm_bo_reserve_slowpath);
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void ttm_bo_unreserve_locked(struct ttm_buffer_object *bo)
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{
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ttm_bo_add_to_lru(bo);
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@ -821,6 +821,36 @@ extern int ttm_bo_reserve(struct ttm_buffer_object *bo,
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bool interruptible,
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bool no_wait, bool use_sequence, uint32_t sequence);
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/**
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* ttm_bo_reserve_slowpath_nolru:
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* @bo: A pointer to a struct ttm_buffer_object.
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* @interruptible: Sleep interruptible if waiting.
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* @sequence: Set (@bo)->sequence to this value after lock
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*
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* This is called after ttm_bo_reserve returns -EAGAIN and we backed off
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* from all our other reservations. Because there are no other reservations
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* held by us, this function cannot deadlock any more.
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*
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* Will not remove reserved buffers from the lru lists.
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* Otherwise identical to ttm_bo_reserve_slowpath.
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*/
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extern int ttm_bo_reserve_slowpath_nolru(struct ttm_buffer_object *bo,
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bool interruptible,
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uint32_t sequence);
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/**
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* ttm_bo_reserve_slowpath:
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* @bo: A pointer to a struct ttm_buffer_object.
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* @interruptible: Sleep interruptible if waiting.
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* @sequence: Set (@bo)->sequence to this value after lock
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*
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* This is called after ttm_bo_reserve returns -EAGAIN and we backed off
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* from all our other reservations. Because there are no other reservations
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* held by us, this function cannot deadlock any more.
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*/
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extern int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,
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bool interruptible, uint32_t sequence);
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/**
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* ttm_bo_reserve_nolru:
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