[PATCH] drm/ttm: fix double lock on glob->lru_lock

Colin King colin.king at canonical.com
Fri Dec 22 18:03:36 UTC 2017

From: Colin Ian King <colin.king at canonical.com>

Lock glob->lru_lock is locked before the while loop and also
locked again at the end of the while loop; it appears that the
lock at the end of the while loop is a double lock that should
be removed.  CoverityScan picked this up with the introduction
of the referenced commit inthe Fixes tag, however, it may have
existed before this.  I've not been able to test this, but it
does look incorrect to me.

Detected by CoverityScan, CID#1268846 ("Double lock")

Fixes: 827ed2b06b05 ("drm/ttm: use try_lock in ttm_bo_delayed_delete again")
Signed-off-by: Colin Ian King <colin.king at canonical.com>
 drivers/gpu/drm/ttm/ttm_bo.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 60bb5c12b568..fb8d13a4bc94 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -595,7 +595,6 @@ static bool ttm_bo_delayed_delete(struct ttm_bo_device *bdev, bool remove_all)
 		kref_put(&bo->list_kref, ttm_bo_release_list);
-		spin_lock(&glob->lru_lock);
 	list_splice_tail(&removed, &bdev->ddestroy);
 	empty = list_empty(&bdev->ddestroy);

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