drbd: Protect accesses to the uuid set with a spinlock

There is at least the worker context, the receiver context, the context of
receiving netlink packts.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index c02d5265c397..d31a0261e83e 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1320,6 +1320,8 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
                 retcode = ERR_NOMEM;
                 goto fail;
         }
+        spin_lock_init(&nbc->md.uuid_lock);
+
         new_disk_conf = kzalloc(sizeof(struct disk_conf), GFP_KERNEL);
         if (!new_disk_conf) {
                 retcode = ERR_NOMEM;
@@ -2679,8 +2681,16 @@ int nla_put_status_info(struct sk_buff *skb, struct drbd_conf *mdev,
                 goto nla_put_failure;
 
         if (got_ldev) {
+                int err;
+
+                spin_lock_irq(&mdev->ldev->md.uuid_lock);
+                err = nla_put(skb, T_uuids, sizeof(si->uuids), mdev->ldev->md.uuid);
+                spin_unlock_irq(&mdev->ldev->md.uuid_lock);
+
+                if (err)
+                        goto nla_put_failure;
+
                 if (nla_put_u32(skb, T_disk_flags, mdev->ldev->md.flags) ||
-                    nla_put(skb, T_uuids, sizeof(si->uuids), mdev->ldev->md.uuid) ||
                     nla_put_u64(skb, T_bits_total, drbd_bm_bits(mdev)) ||
                     nla_put_u64(skb, T_bits_oos, drbd_bm_total_weight(mdev)))
                         goto nla_put_failure;