netdev - [PATCH 3/3] netlink: Lock out table resizes while dumping Netlink sockets

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Message-Id: <e164edeacaeffee43be64d4ed6a5b5e7e8923bd1.1421759056.git.tgraf@suug.ch>
Date:	Tue, 20 Jan 2015 14:20:27 +0100
From:	Thomas Graf <tgraf@...g.ch>
To:	davem@...emloft.net, kaber@...sh.net, herbert@...dor.apana.org.au,
	paulmck@...ux.vnet.ibm.com, ying.xue@...driver.com
Cc:	netdev@...r.kernel.org, netfilter-devel@...r.kernel.org
Subject: [PATCH 3/3] netlink: Lock out table resizes while dumping Netlink sockets

Lock out table resizes while dumping Netlink sockets to user space.
This keeps disruptions to a minimum for readers which don't handle
the NLM_F_DUMP_INTR flag.

Signed-off-by: Thomas Graf <tgraf@...g.ch>
---
 net/netlink/diag.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netlink/diag.c b/net/netlink/diag.c
index 50aa385..be4ea6e 100644
--- a/net/netlink/diag.c
+++ b/net/netlink/diag.c
@@ -114,6 +114,8 @@ static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 	req = nlmsg_data(cb->nlh);
 	cb->seq = atomic_read(&nl_table_seq);
 
+	mutex_lock(&ht->mutex);
+
 	for (i = 0; i < htbl->size; i++) {
 		struct rhash_head *pos;
 
@@ -161,6 +163,7 @@ static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 		num++;
 	}
 done:
+	mutex_unlock(&ht->mutex);
 	cb->args[0] = num;
 	cb->args[1] = protocol;
 
-- 
1.9.3

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