llc: avoid blocking in llc_sap_close()

[ Upstream commit 9708d2b5b7c648e8e0a40d11e8cea12f6277f33c ]

llc_sap_close() is called by llc_sap_put() which
could be called in BH context in llc_rcv(). We can't
block in BH.

There is no reason to block it here, kfree_rcu() should
be sufficient.

Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/net/llc.h b/include/net/llc.h
index 82d9899..95e5ced 100644 (file)
--- a/include/net/llc.h
+++ b/include/net/llc.h
@@ -66,6 +66,7 @@ struct llc_sap {
        int sk_count;
        struct hlist_nulls_head sk_laddr_hash[LLC_SK_LADDR_HASH_ENTRIES];
        struct hlist_head sk_dev_hash[LLC_SK_DEV_HASH_ENTRIES];
+       struct rcu_head rcu;
 };
 
 static inline

diff --git a/net/llc/llc_core.c b/net/llc/llc_core.c
index e896a2c..f1e442a 100644 (file)
--- a/net/llc/llc_core.c
+++ b/net/llc/llc_core.c
@@ -127,9 +127,7 @@ void llc_sap_close(struct llc_sap *sap)
        list_del_rcu(&sap->node);
        spin_unlock_bh(&llc_sap_list_lock);
 
-       synchronize_rcu();
-
-       kfree(sap);
+       kfree_rcu(sap, rcu);
 }
 
 static struct packet_type llc_packet_type __read_mostly = {