[PATCH 2/5] gpu/drm/ttm: Choose a pool to shrink correctly in ttm_dma_pool_shrink_scan().

[Tetsuo Handa]

>From ee941e18a3c05a7589b690669611c3f0895a2d5a Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
Date: Sun, 3 Aug 2014 20:00:40 +0900
Subject: [PATCH 2/5] gpu/drm/ttm: Choose a pool to shrink correctly in 
ttm_dma_pool_shrink_scan().

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 at I-love.SAKURA.ne.jp>
Cc: stable <stable at kernel.org> [3.3+]
---
 drivers/gpu/drm/ttm/ttm_page_alloc_dma.c |    6 +++---
 1 files 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;

-- 
1.7.1