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netlink: add netlink_skb_set_owner_r()

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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@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy 2013-04-17 06:47:00 +00:00 committed by David S. Miller
parent 1298ca4671
commit cf0a018ac6
1 changed files with 17 additions and 3 deletions
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20
net/netlink/af_netlink.c
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@ -119,6 +119,20 @@ 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);
@ -820,7 +834,7 @@ 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;
}
@ -890,7 +904,7 @@ 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);
NETLINK_CB(skb).sk = ssk;
nlk->netlink_rcv(skb);
consume_skb(skb);
@ -962,7 +976,7 @@ static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
!test_bit(NETLINK_CONGESTED, &nlk->state)) {
skb_set_owner_r(skb, sk);
netlink_skb_set_owner_r(skb, sk);
__netlink_sendskb(sk, skb);
return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
}