netdev - [PATCH net v4 1/7] tipc: Refactor __tipc_nl_compat

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Message-ID: <1518586684-12307-2-git-send-email-ying.xue@windriver.com>
Date:   Wed, 14 Feb 2018 13:37:58 +0800
From:   Ying Xue <ying.xue@...driver.com>
To:     <davem@...emloft.net>, <ktkhai@...tuozzo.com>,
        <jon.maloy@...csson.com>
CC:     <netdev@...r.kernel.org>, <syzkaller-bugs@...glegroups.com>,
        <tipc-discussion@...ts.sourceforge.net>
Subject: [PATCH net v4 1/7] 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@...driver.com>
---
 net/tipc/netlink_compat.c | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index e48f0b2..9741690 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);
-- 
2.7.4