netdev - [PATCH net] dccp: don't restart ccid2_hc_tx_rto

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Message-Id: <1516902237-17339-1-git-send-email-alexey.kodanev@oracle.com>
Date:   Thu, 25 Jan 2018 20:43:57 +0300
From:   Alexey Kodanev <alexey.kodanev@...cle.com>
To:     netdev@...r.kernel.org
Cc:     Eric Dumazet <edumazet@...gle.com>,
        David Miller <davem@...emloft.net>, dccp@...r.kernel.org,
        Alexey Kodanev <alexey.kodanev@...cle.com>
Subject: [PATCH net] dccp: don't restart ccid2_hc_tx_rto_expire() if sk in closed state

ccid2_hc_tx_rto_expire() timer callback always restarts the timer
again and can run indefinitely (unless it is stopped outside), and
after commit 120e9dabaf55 ("dccp: defer ccid_hc_tx_delete() at
dismantle time"), which moved sk_stop_timer() to sk_destruct(),
this started to happen quite often. The timer prevents releasing
the socket, as a result, sk_destruct() won't be called.

Found with LTP/dccp_ipsec tests running on the bonding device,
which later couldn't be unloaded after the tests were completed:

  unregister_netdevice: waiting for bond0 to become free. Usage count = 148

Fixes: 120e9dabaf55 ("dccp: defer ccid_hc_tx_delete() at dismantle time")
Signed-off-by: Alexey Kodanev <alexey.kodanev@...cle.com>
---
 net/dccp/ccids/ccid2.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index 1c75cd1..92d016e 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -140,6 +140,9 @@ static void ccid2_hc_tx_rto_expire(struct timer_list *t)

 	ccid2_pr_debug("RTO_EXPIRE\n");

+	if (sk->sk_state == DCCP_CLOSED)
+		goto out;
+
 	/* back-off timer */
 	hc->tx_rto <<= 1;
 	if (hc->tx_rto > DCCP_RTO_MAX)
-- 
1.7.1