linux-kernel - [PATCH 2/3] mm/zsmalloc.c: combine two atomic ops in zs_pool_dec

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Date:   Thu, 24 Jun 2021 20:39:29 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <minchan@...nel.org>,
        <ngupta@...are.org>
CC:     <senozhatsky@...omium.org>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>, <linmiaohe@...wei.com>
Subject: [PATCH 2/3] mm/zsmalloc.c: combine two atomic ops in zs_pool_dec_isolated()

atomic_long_dec_and_test() is equivalent to atomic_long_dec() and
atomic_long_read() == 0. Use it to make code more succinct.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/zsmalloc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 1476289b619f..0b4b23740d78 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1828,13 +1828,12 @@ static void putback_zspage_deferred(struct zs_pool *pool,
 static inline void zs_pool_dec_isolated(struct zs_pool *pool)
 {
 	VM_BUG_ON(atomic_long_read(&pool->isolated_pages) <= 0);
-	atomic_long_dec(&pool->isolated_pages);
 	/*
 	 * There's no possibility of racing, since wait_for_isolated_drain()
 	 * checks the isolated count under &class->lock after enqueuing
 	 * on migration_wait.
 	 */
-	if (atomic_long_read(&pool->isolated_pages) == 0 && pool->destroying)
+	if (atomic_long_dec_and_test(&pool->isolated_pages) && pool->destroying)
 		wake_up_all(&pool->migration_wait);
 }
 
-- 
2.23.0