genl: Fix genl dumpit() locking.

In case of genl-family with parallel ops off, dumpif() callback
is expected to run under genl_lock, But commit def3117493eafd9df
(genl: Allow concurrent genl callbacks.) changed this behaviour
where only first dumpit() op was called under genl-lock.
For subsequent dump, only nlk->cb_lock was taken.
Following patch fixes it by defining locked dumpit() and done()
callback which takes care of genl-locking.

CC: Jesse Gross <jesse@nicira.com>
CC: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 46 insertions, 5 deletions

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 512718adb0d5..7e0f4d199ade 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -544,6 +544,30 @@ void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 }
 EXPORT_SYMBOL(genlmsg_put);
 
+static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
+{
+        struct genl_ops *ops = cb->data;
+        int rc;
+
+        genl_lock();
+        rc = ops->dumpit(skb, cb);
+        genl_unlock();
+        return rc;
+}
+
+static int genl_lock_done(struct netlink_callback *cb)
+{
+        struct genl_ops *ops = cb->data;
+        int rc = 0;
+
+        if (ops->done) {
+                genl_lock();
+                rc = ops->done(cb);
+                genl_unlock();
+        }
+        return rc;
+}
+
 static int genl_family_rcv_msg(struct genl_family *family,
                                struct sk_buff *skb,
                                struct nlmsghdr *nlh)
@@ -572,15 +596,32 @@ static int genl_family_rcv_msg(struct genl_family *family,
                 return -EPERM;
 
         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
-                struct netlink_dump_control c = {
-                        .dump = ops->dumpit,
-                        .done = ops->done,
-                };
+                int rc;
 
                 if (ops->dumpit == NULL)
                         return -EOPNOTSUPP;
 
-                return netlink_dump_start(net->genl_sock, skb, nlh, &c);
+                if (!family->parallel_ops) {
+                        struct netlink_dump_control c = {
+                                .data = ops,
+                                .dump = genl_lock_dumpit,
+                                .done = genl_lock_done,
+                        };
+
+                        genl_unlock();
+                        rc = netlink_dump_start(net->genl_sock, skb, nlh, &c);
+                        genl_lock();
+
+                } else {
+                        struct netlink_dump_control c = {
+                                .dump = ops->dumpit,
+                                .done = ops->done,
+                        };
+
+                        rc = netlink_dump_start(net->genl_sock, skb, nlh, &c);
+                }
+
+                return rc;
         }
 
         if (ops->doit == NULL)