linux-kernel - [PATCH v2 4/4] blk-iocost: read 'ioc->params' inside 'ioc->lock' in ioc_timer

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Message-Id: <20221012094035.390056-5-yukuai1@huaweicloud.com>
Date:   Wed, 12 Oct 2022 17:40:35 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     tj@...nel.org, axboe@...nel.dk
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        yukuai3@...wei.com, yukuai1@...weicloud.com, yi.zhang@...wei.com,
        linan122@...wei.com
Subject: [PATCH v2 4/4] blk-iocost: read 'ioc->params' inside 'ioc->lock' in ioc_timer_fn()

From: Yu Kuai <yukuai3@...wei.com>

'ioc->params' is updated in ioc_refresh_params(), which is proteced by
'ioc->lock', however, ioc_timer_fn() read params outside the lock.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
Acked-by: Tejun Heo <tj@...nel.org>
---
 block/blk-iocost.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 5acc5f13bbd6..f01359906c83 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -2203,8 +2203,8 @@ static void ioc_timer_fn(struct timer_list *timer)
 	LIST_HEAD(surpluses);
 	int nr_debtors, nr_shortages = 0, nr_lagging = 0;
 	u64 usage_us_sum = 0;
-	u32 ppm_rthr = MILLION - ioc->params.qos[QOS_RPPM];
-	u32 ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM];
+	u32 ppm_rthr;
+	u32 ppm_wthr;
 	u32 missed_ppm[2], rq_wait_pct;
 	u64 period_vtime;
 	int prev_busy_level;
@@ -2215,6 +2215,8 @@ static void ioc_timer_fn(struct timer_list *timer)
 	/* take care of active iocgs */
 	spin_lock_irq(&ioc->lock);
 
+	ppm_rthr = MILLION - ioc->params.qos[QOS_RPPM];
+	ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM];
 	ioc_now(ioc, &now);
 
 	period_vtime = now.vnow - ioc->period_at_vtime;
-- 
2.31.1