netdev - [PATCH net 2/3] macsec: RXSAs don't need to hold a reference on RXSCs

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Date:	Fri, 29 Jul 2016 15:37:54 +0200
From:	Sabrina Dubroca <sd@...asysnail.net>
To:	netdev@...r.kernel.org
Cc:	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Sabrina Dubroca <sd@...asysnail.net>
Subject: [PATCH net 2/3] macsec: RXSAs don't need to hold a reference on RXSCs

Following the previous patch, RXSCs are held and properly refcounted in
the RX path (instead of being implicitly held by their SA), so the SA
doesn't need to hold a reference on its parent RXSC.

This also avoids panics on module unload caused by the double layer of
RCU callbacks (call_rcu frees the RXSA, which puts the final reference
on the RXSC and allows to free it in its own call_rcu) that commit
b196c22af5c3 ("macsec: add rcu_barrier() on module exit") didn't
protect against.
There were also some refcounting bugs in macsec_add_rxsa where I didn't
put the reference on the RXSC on the error paths, which would lead to
memory leaks.

Fixes: c09440f7dcb3 ("macsec: introduce IEEE 802.1AE driver")
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
 drivers/net/macsec.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index 718cf98023ff..7f5c5e0f9cf9 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -344,7 +344,6 @@ static void free_rxsa(struct rcu_head *head)

 	crypto_free_aead(sa->key.tfm);
 	free_percpu(sa->stats);
-	macsec_rxsc_put(sa->sc);
 	kfree(sa);
 }

@@ -1653,7 +1652,7 @@ static int macsec_add_rxsa(struct sk_buff *skb, struct genl_info *info)

 	rtnl_lock();
 	rx_sc = get_rxsc_from_nl(genl_info_net(info), attrs, tb_rxsc, &dev, &secy);
-	if (IS_ERR(rx_sc) || !macsec_rxsc_get(rx_sc)) {
+	if (IS_ERR(rx_sc)) {
 		rtnl_unlock();
 		return PTR_ERR(rx_sc);
 	}
-- 
2.9.0