From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 11e504cc705e8ccb06ac93a276e11b5e8fee4d40 upstream.
list_empty(&_manager->pools) being false before taking _manager->lock
does not guarantee that _manager->npools != 0 after taking _manager->lock
because _manager->npools is updated under _manager->lock.
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index 7957beeeaf73..eeb8527aba90 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -1014,6 +1014,8 @@ ttm_dma_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
return SHRINK_STOP;
mutex_lock(&_manager->lock);
+ if (!_manager->npools)
+ goto out;
pool_offset = pool_offset % _manager->npools;
list_for_each_entry(p, &_manager->pools, pools) {
unsigned nr_free;
@@ -1033,6 +1035,7 @@ ttm_dma_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
p->pool->dev_name, p->pool->name, current->pid,
nr_free, shrink_pages);
}
+out:
mutex_unlock(&_manager->lock);
return freed;
}
--
2.1.0
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