For mmap'ed I/O a netlink specific skb destructor needs to be invoked after the
final kfree_skb() to clean up state. This doesn't work currently since the skb's
ownership is transfered to the receiving socket using skb_set_owner_r(), which
orphans the skb, thereby invoking the destructor prematurely.
Since netlink doesn't account skbs to the originating socket, there's no need
to orphan the skb. Add a netlink specific skb_set_owner_r() variant that does
not orphan the skb and use a netlink specific destructor to call sock_rfree().
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
net/netlink/af_netlink.c | 18 ++++++++++++++++--
1 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 3233601..e2d0177 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -166,6 +166,20 @@ static void netlink_consume_callback(struct netlink_callback *cb)
kfree(cb);
}
+static void netlink_skb_destructor(struct sk_buff *skb)
+{
+ sock_rfree(skb);
+}
+
+static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
+{
+ WARN_ON(skb->sk != NULL);
+ skb->sk = sk;
+ skb->destructor = netlink_skb_destructor;
+ atomic_add(skb->truesize, &sk->sk_rmem_alloc);
+ sk_mem_charge(sk, skb->truesize);
+}
+
static void netlink_sock_destruct(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
@@ -855,7 +869,7 @@ int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
}
return 1;
}
- skb_set_owner_r(skb, sk);
+ netlink_skb_set_owner_r(skb, sk);
return 0;
}
@@ -924,7 +938,7 @@ static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb)
ret = -ECONNREFUSED;
if (nlk->netlink_rcv != NULL) {
ret = skb->len;
- skb_set_owner_r(skb, sk);
+ netlink_skb_set_owner_r(skb, sk);
nlk->netlink_rcv(skb);
consume_skb(skb);
} else {
--
1.7.7.6
--
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