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Commit 5e45d7df authored by Maarten Lankhorst's avatar Maarten Lankhorst
Browse files

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: default avatarMaarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: default avatarJerome Glisse <jglisse@redhat.com>
parent 7a186308

drivers/gpu/drm/ttm/ttm_bo.c

+47 −0
Original line number Original line Diff line number Diff line
@@ -310,6 +310,53 @@ int ttm_bo_reserve(struct ttm_buffer_object *bo, 
	return ret;

	return ret;

}

}





int ttm_bo_reserve_slowpath_nolru(struct ttm_buffer_object *bo,

				  bool interruptible, uint32_t sequence)

{

	bool wake_up = false;

	int ret;



	while (unlikely(atomic_xchg(&bo->reserved, 1) != 0)) {

		WARN_ON(bo->seq_valid && sequence == bo->val_seq);



		ret = ttm_bo_wait_unreserved(bo, interruptible);



		if (unlikely(ret))

			return ret;

	}



	if ((bo->val_seq - sequence < (1 << 31)) || !bo->seq_valid)

		wake_up = true;



	/**

	 * Wake up waiters that may need to recheck for deadlock,

	 * if we decreased the sequence number.

	 */

	bo->val_seq = sequence;

	bo->seq_valid = true;

	if (wake_up)

		wake_up_all(&bo->event_queue);



	return 0;

}



int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,

			    bool interruptible, uint32_t sequence)

{

	struct ttm_bo_global *glob = bo->glob;

	int put_count, ret;



	ret = ttm_bo_reserve_slowpath_nolru(bo, interruptible, sequence);

	if (likely(!ret)) {

		spin_lock(&glob->lru_lock);

		put_count = ttm_bo_del_from_lru(bo);

		spin_unlock(&glob->lru_lock);

		ttm_bo_list_ref_sub(bo, put_count, true);

	}

	return ret;

}

EXPORT_SYMBOL(ttm_bo_reserve_slowpath);



void ttm_bo_unreserve_locked(struct ttm_buffer_object *bo)

void ttm_bo_unreserve_locked(struct ttm_buffer_object *bo)

{

{

	ttm_bo_add_to_lru(bo);

	ttm_bo_add_to_lru(bo);

include/drm/ttm/ttm_bo_driver.h

+30 −0
Original line number Original line Diff line number Diff line
@@ -821,6 +821,36 @@ extern int ttm_bo_reserve(struct ttm_buffer_object *bo, 
			  bool interruptible,

			  bool interruptible,

			  bool no_wait, bool use_sequence, uint32_t sequence);

			  bool no_wait, bool use_sequence, uint32_t sequence);





/**

 * ttm_bo_reserve_slowpath_nolru:

 * @bo: A pointer to a struct ttm_buffer_object.

 * @interruptible: Sleep interruptible if waiting.

 * @sequence: Set (@bo)->sequence to this value after lock

 *

 * This is called after ttm_bo_reserve returns -EAGAIN and we backed off

 * from all our other reservations. Because there are no other reservations

 * held by us, this function cannot deadlock any more.

 *

 * Will not remove reserved buffers from the lru lists.

 * Otherwise identical to ttm_bo_reserve_slowpath.

 */

extern int ttm_bo_reserve_slowpath_nolru(struct ttm_buffer_object *bo,

					 bool interruptible,

					 uint32_t sequence);





/**

 * ttm_bo_reserve_slowpath:

 * @bo: A pointer to a struct ttm_buffer_object.

 * @interruptible: Sleep interruptible if waiting.

 * @sequence: Set (@bo)->sequence to this value after lock

 *

 * This is called after ttm_bo_reserve returns -EAGAIN and we backed off

 * from all our other reservations. Because there are no other reservations

 * held by us, this function cannot deadlock any more.

 */

extern int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,

				   bool interruptible, uint32_t sequence);





/**

/**

 * ttm_bo_reserve_nolru:

 * ttm_bo_reserve_nolru: