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drm/ttm: cope with reserved buffers on swap list in ttm_bo_swapout, v2

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Replace the while loop with a simple for each loop, and only run the
delayed destroy cleanup if we can reserve the buffer first.

No race occurs, since lru lock is never dropped any more. An empty list
and a list full of unreservable buffers both cause -EBUSY to be returned,
which is identical to the previous situation.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Maarten Lankhorst 2012-11-28 11:25:42 +00:00 committed by Dave Airlie
parent 85b144f860
commit 2b7b3ad2fb
1 changed files with 16 additions and 32 deletions
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48
drivers/gpu/drm/ttm/ttm_bo.c
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@ -1813,41 +1813,25 @@ static int ttm_bo_swapout(struct ttm_mem_shrink *shrink)
uint32_t swap_placement = (TTM_PL_FLAG_CACHED | TTM_PL_FLAG_SYSTEM);
spin_lock(&glob->lru_lock);
while (ret == -EBUSY) {
if (unlikely(list_empty(&glob->swap_lru))) {
spin_unlock(&glob->lru_lock);
return -EBUSY;
}
bo = list_first_entry(&glob->swap_lru,
struct ttm_buffer_object, swap);
kref_get(&bo->list_kref);
if (!list_empty(&bo->ddestroy)) {
ttm_bo_reserve_locked(bo, false, false, false, 0);
ttm_bo_cleanup_refs_and_unlock(bo, false, false);
kref_put(&bo->list_kref, ttm_bo_release_list);
spin_lock(&glob->lru_lock);
continue;
}
/**
* Reserve buffer. Since we unlock while sleeping, we need
* to re-check that nobody removed us from the swap-list while
* we slept.
*/
list_for_each_entry(bo, &glob->swap_lru, swap) {
ret = ttm_bo_reserve_locked(bo, false, true, false, 0);
if (unlikely(ret == -EBUSY)) {
spin_unlock(&glob->lru_lock);
ttm_bo_wait_unreserved(bo, false);
kref_put(&bo->list_kref, ttm_bo_release_list);
spin_lock(&glob->lru_lock);
}
if (!ret)
break;
}
if (ret) {
spin_unlock(&glob->lru_lock);
return ret;
}
kref_get(&bo->list_kref);
if (!list_empty(&bo->ddestroy)) {
ret = ttm_bo_cleanup_refs_and_unlock(bo, false, false);
kref_put(&bo->list_kref, ttm_bo_release_list);
return ret;
}
BUG_ON(ret != 0);
put_count = ttm_bo_del_from_lru(bo);
spin_unlock(&glob->lru_lock);