This fixes a race pointed out by Dave Airlie where we don't take a buffer object about to be destroyed off the LRU lists properly. It also fixes a rare case where a buffer object could be destroyed in the middle of an accelerated eviction. The patch also adds a utility function that can be used to prematurely release GPU memory space usage of an object waiting to be destroyed. For example during eviction or swapout. Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx> --- drivers/gpu/drm/ttm/ttm_bo.c | 74 +++++++++++++++++++++++++++++++++++------ include/drm/ttm/ttm_bo_api.h | 4 ++- 2 files changed, 66 insertions(+), 12 deletions(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index cb4cf7e..b98cb2c 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -442,6 +442,43 @@ out_err: } /** + * Call bo::reserved and with the lru lock held. + * Will release GPU memory type usage on destruction. + * This is the place to put in driver specific hooks. + * Will release the bo::reserved lock and the + * lru lock on exit. + */ + +static void ttm_bo_cleanup_memtype_use(struct ttm_buffer_object *bo) +{ + struct ttm_bo_global *glob = bo->glob; + + if (bo->ttm) { + + /** + * Release the lru_lock, since we don't want to have + * an atomic requirement on ttm_tt[unbind|destroy]. + */ + + spin_unlock(&glob->lru_lock); + ttm_tt_unbind(bo->ttm); + ttm_tt_destroy(bo->ttm); + bo->ttm = NULL; + spin_lock(&glob->lru_lock); + } + + if (bo->mem.mm_node) { + drm_mm_put_block(bo->mem.mm_node); + bo->mem.mm_node = NULL; + } + + atomic_set(&bo->reserved, 0); + wake_up_all(&bo->event_queue); + spin_unlock(&glob->lru_lock); +} + + +/** * If bo idle, remove from delayed- and lru lists, and unref. * If not idle, and already on delayed list, do nothing. * If not idle, and not on delayed list, put on delayed list, @@ -464,24 +501,39 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo, bool remove_all) spin_unlock(&bo->lock); spin_lock(&glob->lru_lock); - put_count = ttm_bo_del_from_lru(bo); + ret = ttm_bo_reserve_locked(bo, false, true, false, 0); + + /** + * Someone else has the object reserved. Bail and retry. + */ + + if (unlikely(ret != 0)) { + spin_unlock(&glob->lru_lock); + return 0; + } - ret = ttm_bo_reserve_locked(bo, false, false, false, 0); - BUG_ON(ret); - if (bo->ttm) - ttm_tt_unbind(bo->ttm); + /** + * We can re-check for sync object without taking + * the bo::lock since setting the sync object requires + * also bo::reserved. A busy object at this point may + * be caused by another thread starting an accelerated + * eviction. + */ + + if (unlikely(bo->sync_obj)) { + atomic_set(&bo->reserved, 0); + wake_up_all(&bo->event_queue); + spin_unlock(&glob->lru_lock); + } + + put_count = ttm_bo_del_from_lru(bo); if (!list_empty(&bo->ddestroy)) { list_del_init(&bo->ddestroy); ++put_count; } - if (bo->mem.mm_node) { - drm_mm_put_block(bo->mem.mm_node); - bo->mem.mm_node = NULL; - } - spin_unlock(&glob->lru_lock); - atomic_set(&bo->reserved, 0); + ttm_bo_cleanup_memtype_use(bo); while (put_count--) kref_put(&bo->list_kref, ttm_bo_ref_bug); diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h index 267a86c..2040e6c 100644 --- a/include/drm/ttm/ttm_bo_api.h +++ b/include/drm/ttm/ttm_bo_api.h @@ -246,9 +246,11 @@ struct ttm_buffer_object { atomic_t reserved; - /** * Members protected by the bo::lock + * In addition, setting sync_obj to anything else + * than NULL requires bo::reserved to be held. This allows for + * checking NULL while reserved but not holding bo::lock. */ void *sync_obj_arg; -- 1.6.2.5 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel