netdev - [PATCH v2 04/31] net: Move mutex_unlock() in cleanup

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Message-ID: <151120276498.3159.10618037062400965499.stgit@localhost.localdomain>
Date:   Mon, 20 Nov 2017 21:32:45 +0300
From:   Kirill Tkhai <ktkhai@...tuozzo.com>
To:     davem@...emloft.net, vyasevic@...hat.com,
        kstewart@...uxfoundation.org, pombredanne@...b.com,
        vyasevich@...il.com, mark.rutland@....com,
        gregkh@...uxfoundation.org, adobriyan@...il.com, fw@...len.de,
        nicolas.dichtel@...nd.com, xiyou.wangcong@...il.com,
        roman.kapl@...go.com, paul@...l-moore.com, dsahern@...il.com,
        daniel@...earbox.net, lucien.xin@...il.com,
        mschiffer@...verse-factory.net, rshearma@...cade.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        ktkhai@...tuozzo.com, ebiederm@...ssion.com, avagin@...tuozzo.com,
        gorcunov@...tuozzo.com, eric.dumazet@...il.com,
        stephen@...workplumber.org, ktkhai@...tuozzo.com
Subject: [PATCH v2 04/31] net: Move mutex_unlock() in cleanup_net() up

net_sem protects from pernet_list changing, while
ops_free_list() makes simple kfree(), and it can't
race with other pernet_operations callbacks.

So we may release net_mutex earlier then it was.

Signed-off-by: Kirill Tkhai <ktkhai@...tuozzo.com>
---
 net/core/net_namespace.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 859dce31e37e..c4f7452906bb 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -489,11 +489,12 @@ static void cleanup_net(struct work_struct *work)
 	list_for_each_entry_reverse(ops, &pernet_list, list)
 		ops_exit_list(ops, &net_exit_list);
 
+	mutex_unlock(&net_mutex);
+
 	/* Free the net generic variables */
 	list_for_each_entry_reverse(ops, &pernet_list, list)
 		ops_free_list(ops, &net_exit_list);
 
-	mutex_unlock(&net_mutex);
 	up_read(&net_sem);
 
 	/* Ensure there are no outstanding rcu callbacks using this