linux-kernel - [PATCH] memcg: remove some redundant checks

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Message-ID: <4A1645CC.8000600@cn.fujitsu.com>
Date:	Fri, 22 May 2009 14:27:24 +0800
From:	Li Zefan <lizf@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: [PATCH] memcg: remove some redundant checks

We don't need to check do_swap_account in the case that the
function which checks do_swap_account will never get called if
do_swap_account == 0.

Signed-off-by: Li Zefan <lizf@...fujitsu.com>
---
 memcontrol.c  |   11 ++++-------
 page_cgroup.c |    8 --------
 2 files changed, 4 insertions(+), 15 deletions(-)

--- a/mm/memcontrol.c	2009-05-22 11:38:06.000000000 +0800
+++ b/mm/memcontrol.c	2009-05-22 11:40:38.000000000 +0800
@@ -45,7 +45,7 @@ struct cgroup_subsys mem_cgroup_subsys _
 #define MEM_CGROUP_RECLAIM_RETRIES	5
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
-/* Turned on only when memory cgroup is enabled && really_do_swap_account = 0 */
+/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
 int do_swap_account __read_mostly;
 static int really_do_swap_account __initdata = 1; /* for remember boot option*/
 #else
@@ -1771,16 +1771,14 @@ static int mem_cgroup_resize_limit(struc
 	return ret;
 }
 
-int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
-				unsigned long long val)
+static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
+					unsigned long long val)
 {
 	int retry_count;
 	u64 memlimit, oldusage, curusage;
 	int children = mem_cgroup_count_children(memcg);
 	int ret = -EBUSY;
 
-	if (!do_swap_account)
-		return -EINVAL;
 	/* see mem_cgroup_resize_res_limit */
  	retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
 	oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
@@ -2015,8 +2013,7 @@ static u64 mem_cgroup_read(struct cgroup
 		val = res_counter_read_u64(&mem->res, name);
 		break;
 	case _MEMSWAP:
-		if (do_swap_account)
-			val = res_counter_read_u64(&mem->memsw, name);
+		val = res_counter_read_u64(&mem->memsw, name);
 		break;
 	default:
 		BUG();
--- a/mm/page_cgroup.c	2009-05-22 11:41:35.000000000 +0800
+++ b/mm/page_cgroup.c	2009-05-22 11:44:13.000000000 +0800
@@ -316,8 +316,6 @@ static int swap_cgroup_prepare(int type)
 	struct swap_cgroup_ctrl *ctrl;
 	unsigned long idx, max;
 
-	if (!do_swap_account)
-		return 0;
 	ctrl = &swap_cgroup_ctrl[type];
 
 	for (idx = 0; idx < ctrl->length; idx++) {
@@ -354,9 +352,6 @@ unsigned short swap_cgroup_record(swp_en
 	struct swap_cgroup *sc;
 	unsigned short old;
 
-	if (!do_swap_account)
-		return 0;
-
 	ctrl = &swap_cgroup_ctrl[type];
 
 	mappage = ctrl->map[idx];
@@ -385,9 +380,6 @@ unsigned short lookup_swap_cgroup(swp_en
 	struct swap_cgroup *sc;
 	unsigned short ret;
 
-	if (!do_swap_account)
-		return 0;
-
 	ctrl = &swap_cgroup_ctrl[type];
 	mappage = ctrl->map[idx];
 	sc = page_address(mappage);
--
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