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@xxxxxxxxxx>
---
drivers/gpu/drm/ttm/ttm_bo.c | 22 +++++++++++++---------
1 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index d42631c..043cd33 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
@@ -810,11 +817,8 @@ retry:
ret = ttm_bo_cleanup_refs(bo, interruptible,
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);
--
1.7.4.4
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