tipc: Refactor __tipc_nl_compat_doit

As preparation for adding RTNL to make (*cmd->transcode)() and
(*cmd->transcode)() constantly protected by RTNL lock, we move out of
memory allocations existing between them as many as possible so that
the time of holding RTNL can be minimized in __tipc_nl_compat_doit().

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 14 deletions

diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index e48f0b2c01b9..974169059b9c 100644
--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -285,10 +285,6 @@ static int __tipc_nl_compat_doit(struct tipc_nl_compat_cmd_doit *cmd,
         if (!trans_buf)
                 return -ENOMEM;
 
-        err = (*cmd->transcode)(cmd, trans_buf, msg);
-        if (err)
-                goto trans_out;
-
         attrbuf = kmalloc((tipc_genl_family.maxattr + 1) *
                         sizeof(struct nlattr *), GFP_KERNEL);
         if (!attrbuf) {
@@ -296,27 +292,32 @@ static int __tipc_nl_compat_doit(struct tipc_nl_compat_cmd_doit *cmd,
                 goto trans_out;
         }
 
-        err = nla_parse(attrbuf, tipc_genl_family.maxattr,
-                        (const struct nlattr *)trans_buf->data,
-                        trans_buf->len, NULL, NULL);
-        if (err)
-                goto parse_out;
-
         doit_buf = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
         if (!doit_buf) {
                 err = -ENOMEM;
-                goto parse_out;
+                goto attrbuf_out;
         }
 
-        doit_buf->sk = msg->dst_sk;
-
         memset(&info, 0, sizeof(info));
         info.attrs = attrbuf;
 
+        err = (*cmd->transcode)(cmd, trans_buf, msg);
+        if (err)
+                goto doit_out;
+
+        err = nla_parse(attrbuf, tipc_genl_family.maxattr,
+                        (const struct nlattr *)trans_buf->data,
+                        trans_buf->len, NULL, NULL);
+        if (err)
+                goto doit_out;
+
+        doit_buf->sk = msg->dst_sk;
+
         err = (*cmd->doit)(doit_buf, &info);
+doit_out:
 
         kfree_skb(doit_buf);
-parse_out:
+attrbuf_out:
         kfree(attrbuf);
 trans_out:
         kfree_skb(trans_buf);