netdev - [PATCH net-next 6/9] net/packet: convert po->tp

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Date:   Thu, 16 Mar 2023 01:10:11 +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 6/9] net/packet: convert po->tp_loss to an atomic flag

tp_loss can be read locklessly.

Convert it to an atomic flag to avoid races.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/packet/af_packet.c | 6 +++---
 net/packet/diag.c      | 2 +-
 net/packet/internal.h  | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 7800dc622ff37d059e43c96d2d7f293905b3d5af..119063c8a1c590b715fa570354f561bfa7df5301 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2843,7 +2843,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
 
 		if (unlikely(tp_len < 0)) {
 tpacket_error:
-			if (po->tp_loss) {
+			if (packet_sock_flag(po, PACKET_SOCK_TP_LOSS)) {
 				__packet_set_status(po, ph,
 						TP_STATUS_AVAILABLE);
 				packet_increment_head(&po->tx_ring);
@@ -3886,7 +3886,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval,
 		if (po->rx_ring.pg_vec || po->tx_ring.pg_vec) {
 			ret = -EBUSY;
 		} else {
-			po->tp_loss = !!val;
+			packet_sock_flag_set(po, PACKET_SOCK_TP_LOSS, val);
 			ret = 0;
 		}
 		release_sock(sk);
@@ -4095,7 +4095,7 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
 		val = po->tp_reserve;
 		break;
 	case PACKET_LOSS:
-		val = po->tp_loss;
+		val = packet_sock_flag(po, PACKET_SOCK_TP_LOSS);
 		break;
 	case PACKET_TIMESTAMP:
 		val = READ_ONCE(po->tp_tstamp);
diff --git a/net/packet/diag.c b/net/packet/diag.c
index 0abca32e2f878b419814709afb8d1d5b282d0597..8bb4ce6a8e6171fef43988fe83b0adc8100fe866 100644
--- a/net/packet/diag.c
+++ b/net/packet/diag.c
@@ -29,7 +29,7 @@ static int pdiag_put_info(const struct packet_sock *po, struct sk_buff *nlskb)
 		pinfo.pdi_flags |= PDI_ORIGDEV;
 	if (po->has_vnet_hdr)
 		pinfo.pdi_flags |= PDI_VNETHDR;
-	if (po->tp_loss)
+	if (packet_sock_flag(po, PACKET_SOCK_TP_LOSS))
 		pinfo.pdi_flags |= PDI_LOSS;
 
 	return nla_put(nlskb, PACKET_DIAG_INFO, sizeof(pinfo), &pinfo);
diff --git a/net/packet/internal.h b/net/packet/internal.h
index 0d16a581e27132988942bcc71da223f7c30ac00c..9d406a92ede8e917089943b39a0fe97b064599f3 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -118,8 +118,7 @@ struct packet_sock {
 	struct mutex		pg_vec_lock;
 	unsigned long		flags;
 	unsigned int		running;	/* bind_lock must be held */
-	unsigned int		has_vnet_hdr:1, /* writer must hold sock lock */
-				tp_loss:1;
+	unsigned int		has_vnet_hdr:1; /* writer must hold sock lock */
 	int			pressure;
 	int			ifindex;	/* bound device		*/
 	__be16			num;
@@ -146,6 +145,7 @@ enum packet_sock_flags {
 	PACKET_SOCK_ORIGDEV,
 	PACKET_SOCK_AUXDATA,
 	PACKET_SOCK_TX_HAS_OFF,
+	PACKET_SOCK_TP_LOSS,
 };
 
 static inline void packet_sock_flag_set(struct packet_sock *po,
-- 
2.40.0.rc2.332.ga46443480c-goog