[md PATCH 16/18] md/multipath: add rcu protection to rdev access in multipath_status.

NeilBrown
2016-06-02T06:19:52Z

drivers/md/multipath.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index dd483bb2e111..69244de2036b 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -141,17 +141,19 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio)
return;
}

-static void multipath_status (struct seq_file *seq, struct mddev *mddev)
+static void multipath_status(struct seq_file *seq, struct mddev *mddev)
{
struct mpconf *conf = mddev->private;
int i;

seq_printf (seq, " [%d/%d] [", conf->raid_disks,
conf->raid_disks - mddev->degraded);
- for (i = 0; i < conf->raid_disks; i++)
- seq_printf (seq, "%s",
- conf->multipaths[i].rdev &&
- test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
+ rcu_read_lock();
+ for (i = 0; i < conf->raid_disks; i++) {
+ struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
+ seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
+ }
+ rcu_read_unlock();
seq_printf (seq, "]");
}