[PATCH -next 01/29] md: use READ_ONCE/WRITE_ONCE for 'suspend_lo' and 'suspend_hi'

From: Yu Kuai
Date: Thu Aug 03 2023 - 09:34:27 EST


From: Yu Kuai <yukuai3@xxxxxxxxxx>

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@xxxxxxxxxx>
---
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 55a74d9b7457..5aa9f62a7c56 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -358,11 +358,11 @@ 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;
}
@@ -5174,7 +5174,8 @@ __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
@@ -5194,7 +5195,7 @@ 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);
@@ -5206,7 +5207,8 @@ __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
@@ -5226,7 +5228,7 @@ 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