diff mbox series

[-next,v3,01/25] md: use READ_ONCE/WRITE_ONCE for 'suspend_lo' and 'suspend_hi'

Message ID 20230928061543.1845742-2-yukuai1@huaweicloud.com (mailing list archive)
State New, archived
Delegated to: Song Liu
Headers show
Series md: synchronize io with array reconfiguration | expand

Commit Message

Yu Kuai Sept. 28, 2023, 6:15 a.m. UTC 
From: Yu Kuai <yukuai3@huawei.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@huawei.com>
---
 drivers/md/md.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

Comments

Song Liu Sept. 28, 2023, 3:54 p.m. UTC | #1 
On Wed, Sep 27, 2023 at 11:22 PM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@huawei.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.

I rephrase this a bit:

Protect 'suspend_lo' and 'suspend_hi' with READ_ONCE/WRITE_ONCE to prevent
reading abnormal values.

Thanks,
Song
diff mbox series

Patch

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 0b83a406e797..18a0f12dbf5f 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;
 }
@@ -5176,7 +5176,8 @@  __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
@@ -5196,7 +5197,7 @@  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);
@@ -5208,7 +5209,8 @@  __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
@@ -5228,7 +5230,7 @@  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);