linux-kernel - [PATCH -next v2 01/28] md: use READ_ONCE/WRITE_ONCE for 'suspend_lo' and 'suspend

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Message-Id: <20230828020021.2489641-2-yukuai1@huaweicloud.com>
Date:   Mon, 28 Aug 2023 09:59:54 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     agk@...hat.com, snitzer@...nel.org, dm-devel@...hat.com,
        song@...nel.org, xni@...hat.com
Cc:     linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org,
        yukuai3@...wei.com, yukuai1@...weicloud.com, yi.zhang@...wei.com,
        yangerkun@...wei.com
Subject: [PATCH -next v2 01/28] md: use READ_ONCE/WRITE_ONCE for 'suspend_lo' and 'suspend_hi'

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

Because reading 'suspend_lo' and 'suspend_hi' from md_handle_request()
is not protected, use READ_ONCE/WRITE_ONCE to prevent reading abnormal
value.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 drivers/md/md.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 46badd13a687..9d8dff9d923c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -359,11 +359,11 @@ static bool is_suspended(struct mddev *mddev, struct bio *bio)
 		return true;
 	if (bio_data_dir(bio) != WRITE)
 		return false;
-	if (mddev->suspend_lo >= mddev->suspend_hi)
+	if (READ_ONCE(mddev->suspend_lo) >= READ_ONCE(mddev->suspend_hi))
 		return false;
-	if (bio->bi_iter.bi_sector >= mddev->suspend_hi)
+	if (bio->bi_iter.bi_sector >= READ_ONCE(mddev->suspend_hi))
 		return false;
-	if (bio_end_sector(bio) < mddev->suspend_lo)
+	if (bio_end_sector(bio) < READ_ONCE(mddev->suspend_lo))
 		return false;
 	return true;
 }
@@ -5171,7 +5171,8 @@ __ATTR(sync_max, S_IRUGO|S_IWUSR, max_sync_show, max_sync_store);
 static ssize_t
 suspend_lo_show(struct mddev *mddev, char *page)
 {
-	return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)READ_ONCE(mddev->suspend_lo));
 }
 
 static ssize_t
@@ -5191,7 +5192,7 @@ suspend_lo_store(struct mddev *mddev, const char *buf, size_t len)
 		return err;
 
 	mddev_suspend(mddev);
-	mddev->suspend_lo = new;
+	WRITE_ONCE(mddev->suspend_lo, new);
 	mddev_resume(mddev);
 
 	mddev_unlock(mddev);
@@ -5203,7 +5204,8 @@ __ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);
 static ssize_t
 suspend_hi_show(struct mddev *mddev, char *page)
 {
-	return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)READ_ONCE(mddev->suspend_hi));
 }
 
 static ssize_t
@@ -5223,7 +5225,7 @@ suspend_hi_store(struct mddev *mddev, const char *buf, size_t len)
 		return err;
 
 	mddev_suspend(mddev);
-	mddev->suspend_hi = new;
+	WRITE_ONCE(mddev->suspend_hi, new);
 	mddev_resume(mddev);
 
 	mddev_unlock(mddev);
-- 
2.39.2