[PATCH 3.13 146/187] drm/ttm: Choose a pool to shrink correctly in ttm_dma_pool_shrink_scan().

Kamal Mostafa
2014-09-15T23:06:22Z

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

commit 46c2df68f03a236b30808bba361f10900c88d95e upstream.

We can use "unsigned int" instead of "atomic_t" by updating start_pool
variable under _manager->lock. This patch will make it possible to avoid
skipping when choosing a pool to shrink in round-robin style, after next
patch changes mutex_lock(_manager->lock) to !mutex_trylock(_manager->lork).

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index b751fff..d8e59f7 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -1004,9 +1004,9 @@ EXPORT_SYMBOL_GPL(ttm_dma_unpopulate);
static unsigned long
ttm_dma_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
{
- static atomic_t start_pool = ATOMIC_INIT(0);
+ static unsigned start_pool;
unsigned idx = 0;
- unsigned pool_offset = atomic_add_return(1, &start_pool);
+ unsigned pool_offset;
unsigned shrink_pages = sc->nr_to_scan;
struct device_pools *p;
unsigned long freed = 0;
@@ -1017,7 +1017,7 @@ ttm_dma_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
mutex_lock(&_manager->lock);
if (!_manager->npools)
goto out;
- pool_offset = pool_offset % _manager->npools;
+ pool_offset = ++start_pool % _manager->npools;
list_for_each_entry(p, &_manager->pools, pools) {
unsigned nr_free;

--
1.9.1