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net/packet: annotate accesses to po->xmit

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po->xmit can be set from setsockopt(PACKET_QDISC_BYPASS),
while read locklessly.

Use READ_ONCE()/WRITE_ONCE() to avoid potential load/store
tearing issues.

Fixes: d346a3fae3 ("packet: introduce PACKET_QDISC_BYPASS socket option")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2023-03-16 01:10:06 +00:00 committed by David S. Miller
parent dc021e6c24
commit b9d83ab8a7
1 changed files with 8 additions and 4 deletions
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12
net/packet/af_packet.c
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@ -307,7 +307,8 @@ static void packet_cached_dev_reset(struct packet_sock *po)
static bool packet_use_direct_xmit(const struct packet_sock *po)
{
return po->xmit == packet_direct_xmit;
/* Paired with WRITE_ONCE() in packet_setsockopt() */
return READ_ONCE(po->xmit) == packet_direct_xmit;
}
static u16 packet_pick_tx_queue(struct sk_buff *skb)
@ -2867,7 +2868,8 @@ tpacket_error:
packet_inc_pending(&po->tx_ring);
status = TP_STATUS_SEND_REQUEST;
err = po->xmit(skb);
/* Paired with WRITE_ONCE() in packet_setsockopt() */
err = READ_ONCE(po->xmit)(skb);
if (unlikely(err != 0)) {
if (err > 0)
err = net_xmit_errno(err);
@ -3070,7 +3072,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
virtio_net_hdr_set_proto(skb, &vnet_hdr);
}
err = po->xmit(skb);
/* Paired with WRITE_ONCE() in packet_setsockopt() */
err = READ_ONCE(po->xmit)(skb);
if (unlikely(err != 0)) {
if (err > 0)
err = net_xmit_errno(err);
@ -4007,7 +4010,8 @@ packet_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval,
if (copy_from_sockptr(&val, optval, sizeof(val)))
return -EFAULT;
po->xmit = val ? packet_direct_xmit : dev_queue_xmit;
/* Paired with all lockless reads of po->xmit */
WRITE_ONCE(po->xmit, val ? packet_direct_xmit : dev_queue_xmit);
return 0;
}
default: