[dm-devel] [PATCH -next v2 01/28] md: use READ_ONCE/WRITE_ONCE for 'suspend_lo' and 'suspend_hi'

[Yu Kuai]

From: Yu Kuai <yuku...@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 <yuku...@huawei.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

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