linux-kernel - [PATCH] blk-throttle: don't check whether or not lower limit is valid if CONFIG_BLK_DEV_THROTTLING

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20201126031834.40807-1-yukuai3@huawei.com>
Date:   Thu, 26 Nov 2020 11:18:34 +0800
From:   Yu Kuai <yukuai3@...wei.com>
To:     <tj@...nel.org>, <axboe@...nel.dk>
CC:     <cgroups@...r.kernel.org>, <linux-block@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <yukuai3@...wei.com>,
        <yi.zhang@...wei.com>, <zhangxiaoxu5@...wei.com>
Subject: [PATCH] blk-throttle: don't check whether or not lower limit is valid if CONFIG_BLK_DEV_THROTTLING_LOW is off

blk_throtl_update_limit_valid() will search for descendants to see if
'LIMIT_LOW' of bps/iops and READ/WRITE is nonzero. However, they're always
zero if CONFIG_BLK_DEV_THROTTLING_LOW is not set, furthermore, a lot of
time will be wasted to iterate descendants.

Thus do nothing in blk_throtl_update_limit_valid() in such situation.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 block/blk-throttle.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index b771c4299982..d52cac9f3a7c 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -587,6 +587,7 @@ static void throtl_pd_online(struct blkg_policy_data *pd)
 	tg_update_has_rules(tg);
 }
 
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
 static void blk_throtl_update_limit_valid(struct throtl_data *td)
 {
 	struct cgroup_subsys_state *pos_css;
@@ -607,6 +608,11 @@ static void blk_throtl_update_limit_valid(struct throtl_data *td)
 
 	td->limit_valid[LIMIT_LOW] = low_valid;
 }
+#else
+static inline void blk_throtl_update_limit_valid(struct throtl_data *td)
+{
+}
+#endif
 
 static void throtl_upgrade_state(struct throtl_data *td);
 static void throtl_pd_offline(struct blkg_policy_data *pd)
-- 
2.25.4