drm/ttm: Choose a pool to shrink correctly in ttm_dma_pool_shrink_scan().

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index e9f65ad2a0eba3c7f5eba59d3344c26ddd366dd6..de1a753b1d563549a652987872a01d995c1782e3 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -1006,9 +1006,9 @@ EXPORT_SYMBOL_GPL(ttm_dma_unpopulate);
 static int ttm_dma_pool_mm_shrink(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;
 
@@ -1018,7 +1018,7 @@ static int ttm_dma_pool_mm_shrink(struct shrinker *shrink,
        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;