linux-kernel - [PATCH 2/5] gpu/drm/ttm: Choose a pool to shrink correctly in ttm_dma_pool_shrink

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Message-Id: <201405311159.CHG64048.SOFLQHVtFOMFJO@I-love.SAKURA.ne.jp>
Date:	Sat, 31 May 2014 11:59:39 +0900
From:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:	konrad.wilk@...cle.com
Cc:	dchinner@...hat.com, airlied@...ux.ie, glommer@...nvz.org,
	mgorman@...e.de, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH 2/5] gpu/drm/ttm: Choose a pool to shrink correctly in ttm_dma_pool_shrink_scan().

>>From 19927a63c5d2dcda467373c31d810be42e40e190 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Date: Sat, 31 May 2014 09:47:02 +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@...ove.SAKURA.ne.jp>
Cc: stable <stable@...nel.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
--
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