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drm/ttm: add ttm_bo_reserve_slowpath

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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>
This commit is contained in:
Maarten Lankhorst 2013-01-15 14:57:05 +01:00
parent 7a1863084c
commit 5e45d7dfd7
2 changed files with 77 additions and 0 deletions
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47
drivers/gpu/drm/ttm/ttm_bo.c
View file

@ -310,6 +310,53 @@ int ttm_bo_reserve(struct ttm_buffer_object *bo,
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)
{
ttm_bo_add_to_lru(bo);

30
include/drm/ttm/ttm_bo_driver.h
View file

@ -821,6 +821,36 @@ extern int ttm_bo_reserve(struct ttm_buffer_object *bo,
bool interruptible,
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: