diff options
| author | Thomas Hellstrom <thellstrom@vmware.com> | 2012-10-22 12:51:26 +0000 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2012-10-23 10:15:21 +1000 |
| commit | b8e902f24fdd16c4373ddc37a4e150c4afe9c6db (patch) | |
| tree | e17556304d126329c63af9367432fe796294d08a /drivers/gpu/drm | |
| parent | 7bc17a7837bf4ec8fd2d63438c0b6b0160c454c1 (diff) | |
| download | linux-b8e902f24fdd16c4373ddc37a4e150c4afe9c6db.tar.bz2 | |
drm/ttm: Fix a theoretical race in ttm_bo_cleanup_refs()
In theory, that function could release the lru lock between
checking for bo on ddestroy list and a successful reserve if the bo
was already reserved, and the function was called with waiting reserves
allowed.
However, all current reservers of a bo on the ddestroy list would
atomically take the bo off the list after a successful reserve so this
race should not have been hit, so no need to backport for stable.
This patch also fixes a case found by Maarten Lankhorst where
ttm_mem_evict_first called with no_wait_gpu would incorrectly
spin waiting for bo idle if trying to evict a busy buffer that
also sits on the ddestroy list.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers/gpu/drm')
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_bo.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index d42631cade5a..bf6e4b5a73b5 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -580,6 +580,7 @@ retry: if (unlikely(ret != 0)) return ret; +retry_reserve: spin_lock(&glob->lru_lock); if (unlikely(list_empty(&bo->ddestroy))) { @@ -587,14 +588,20 @@ retry: return 0; } - ret = ttm_bo_reserve_locked(bo, interruptible, - no_wait_reserve, false, 0); + ret = ttm_bo_reserve_locked(bo, false, true, false, 0); - if (unlikely(ret != 0)) { + if (unlikely(ret == -EBUSY)) { spin_unlock(&glob->lru_lock); - return ret; + if (likely(!no_wait_reserve)) + ret = ttm_bo_wait_unreserved(bo, interruptible); + if (unlikely(ret != 0)) + return ret; + + goto retry_reserve; } + BUG_ON(ret != 0); + /** * We can re-check for sync object without taking * the bo::lock since setting the sync object requires @@ -811,10 +818,7 @@ retry: no_wait_reserve, no_wait_gpu); kref_put(&bo->list_kref, ttm_bo_release_list); - if (likely(ret == 0 || ret == -ERESTARTSYS)) - return ret; - - goto retry; + return ret; } ret = ttm_bo_reserve_locked(bo, false, true, false, 0); |