netdev - [PATCH net-next 4/9] net/packet: annotate accesses to po->tp

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Date:   Thu, 16 Mar 2023 01:10:09 +0000
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     netdev@...r.kernel.org, Willem de Bruijn <willemb@...gle.com>,
        eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 4/9] net/packet: annotate accesses to po->tp_tstamp

tp_tstamp is read locklessly.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/packet/af_packet.c | 9 +++++----
 net/packet/diag.c      | 2 +-
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index ecd9fc27e360cc85be35de568e6ebcb2dbbd9d39..a27a811fa2b0d0b267cf42d5b411503587e2dccb 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -474,7 +474,7 @@ static __u32 __packet_set_timestamp(struct packet_sock *po, void *frame,
 	struct timespec64 ts;
 	__u32 ts_status;
 
-	if (!(ts_status = tpacket_get_timestamp(skb, &ts, po->tp_tstamp)))
+	if (!(ts_status = tpacket_get_timestamp(skb, &ts, READ_ONCE(po->tp_tstamp))))
 		return 0;
 
 	h.raw = frame;
@@ -2403,7 +2403,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 	 * closer to the time of capture.
 	 */
 	ts_status = tpacket_get_timestamp(skb, &ts,
-					  po->tp_tstamp | SOF_TIMESTAMPING_SOFTWARE);
+					  READ_ONCE(po->tp_tstamp) |
+					  SOF_TIMESTAMPING_SOFTWARE);
 	if (!ts_status)
 		ktime_get_real_ts64(&ts);
 
@@ -3945,7 +3946,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval,
 		if (copy_from_sockptr(&val, optval, sizeof(val)))
 			return -EFAULT;
 
-		po->tp_tstamp = val;
+		WRITE_ONCE(po->tp_tstamp, val);
 		return 0;
 	}
 	case PACKET_FANOUT:
@@ -4097,7 +4098,7 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
 		val = po->tp_loss;
 		break;
 	case PACKET_TIMESTAMP:
-		val = po->tp_tstamp;
+		val = READ_ONCE(po->tp_tstamp);
 		break;
 	case PACKET_FANOUT:
 		val = (po->fanout ?
diff --git a/net/packet/diag.c b/net/packet/diag.c
index d704c7bf51b2073f792ff35c1f46fba251dd4761..0abca32e2f878b419814709afb8d1d5b282d0597 100644
--- a/net/packet/diag.c
+++ b/net/packet/diag.c
@@ -18,7 +18,7 @@ static int pdiag_put_info(const struct packet_sock *po, struct sk_buff *nlskb)
 	pinfo.pdi_version = po->tp_version;
 	pinfo.pdi_reserve = po->tp_reserve;
 	pinfo.pdi_copy_thresh = po->copy_thresh;
-	pinfo.pdi_tstamp = po->tp_tstamp;
+	pinfo.pdi_tstamp = READ_ONCE(po->tp_tstamp);
 
 	pinfo.pdi_flags = 0;
 	if (po->running)
-- 
2.40.0.rc2.332.ga46443480c-goog