net: add sk_drops_read(), sk_drops_inc() and sk_drops_reset() helpers

We want to split sk->sk_drops in the future to reduce
potential contention on this field.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250826125031.1578842-2-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

15 files changed, 40 insertions, 40 deletions

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 94cc4705e91d..ba8253aa6e07 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -345,7 +345,7 @@ int __sk_queue_drop_skb(struct sock *sk, struct sk_buff_head *sk_queue,
 		spin_unlock_bh(&sk_queue->lock);
 	}
 
-	atomic_inc(&sk->sk_drops);
+	sk_drops_inc(sk);
 	return err;
 }
 EXPORT_SYMBOL(__sk_queue_drop_skb);
diff --git a/net/core/sock.c b/net/core/sock.c
index 8002ac6293dc..75368823969a 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -491,13 +491,13 @@ int __sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	struct sk_buff_head *list = &sk->sk_receive_queue;
 
 	if (atomic_read(&sk->sk_rmem_alloc) >= READ_ONCE(sk->sk_rcvbuf)) {
-		atomic_inc(&sk->sk_drops);
+		sk_drops_inc(sk);
 		trace_sock_rcvqueue_full(sk, skb);
 		return -ENOMEM;
 	}
 
 	if (!sk_rmem_schedule(sk, skb, skb->truesize)) {
-		atomic_inc(&sk->sk_drops);
+		sk_drops_inc(sk);
 		return -ENOBUFS;
 	}
 
@@ -562,7 +562,7 @@ int __sk_receive_skb(struct sock *sk, struct sk_buff *skb,
 	skb->dev = NULL;
 
 	if (sk_rcvqueues_full(sk, READ_ONCE(sk->sk_rcvbuf))) {
-		atomic_inc(&sk->sk_drops);
+		sk_drops_inc(sk);
 		reason = SKB_DROP_REASON_SOCKET_RCVBUFF;
 		goto discard_and_relse;
 	}
@@ -585,7 +585,7 @@ int __sk_receive_skb(struct sock *sk, struct sk_buff *skb,
 			reason = SKB_DROP_REASON_PFMEMALLOC;
 		if (err == -ENOBUFS)
 			reason = SKB_DROP_REASON_SOCKET_BACKLOG;
-		atomic_inc(&sk->sk_drops);
+		sk_drops_inc(sk);
 		goto discard_and_relse;
 	}
 
@@ -2505,7 +2505,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
 	newsk->sk_wmem_queued	= 0;
 	newsk->sk_forward_alloc = 0;
 	newsk->sk_reserved_mem  = 0;
-	atomic_set(&newsk->sk_drops, 0);
+	sk_drops_reset(newsk);
 	newsk->sk_send_head	= NULL;
 	newsk->sk_userlocks	= sk->sk_userlocks & ~SOCK_BINDPORT_LOCK;
 	atomic_set(&newsk->sk_zckey, 0);
@@ -3713,7 +3713,7 @@ void sock_init_data_uid(struct socket *sock, struct sock *sk, kuid_t uid)
 	 */
 	smp_wmb();
 	refcount_set(&sk->sk_refcnt, 1);
-	atomic_set(&sk->sk_drops, 0);
+	sk_drops_reset(sk);
 }
 EXPORT_SYMBOL(sock_init_data_uid);
 
@@ -3973,7 +3973,7 @@ void sk_get_meminfo(const struct sock *sk, u32 *mem)
 	mem[SK_MEMINFO_WMEM_QUEUED] = READ_ONCE(sk->sk_wmem_queued);
 	mem[SK_MEMINFO_OPTMEM] = atomic_read(&sk->sk_omem_alloc);
 	mem[SK_MEMINFO_BACKLOG] = READ_ONCE(sk->sk_backlog.len);
-	mem[SK_MEMINFO_DROPS] = atomic_read(&sk->sk_drops);
+	mem[SK_MEMINFO_DROPS] = sk_drops_read(sk);
 }
 
 #ifdef CONFIG_PROC_FS
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 031df4c19fcc..f119da68fc30 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -1119,7 +1119,7 @@ static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
 		from_kuid_munged(seq_user_ns(f), sk_uid(sp)),
 		0, sock_i_ino(sp),
 		refcount_read(&sp->sk_refcnt), sp,
-		atomic_read(&sp->sk_drops));
+		sk_drops_read(sp));
 }
 
 static int ping_v4_seq_show(struct seq_file *seq, void *v)
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 1d2c89d63cc7..0f9f02f6146e 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -178,7 +178,7 @@ static int raw_v4_input(struct net *net, struct sk_buff *skb,
 
 		if (atomic_read(&sk->sk_rmem_alloc) >=
 		    READ_ONCE(sk->sk_rcvbuf)) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			continue;
 		}
 
@@ -311,7 +311,7 @@ static int raw_rcv_skb(struct sock *sk, struct sk_buff *skb)
 int raw_rcv(struct sock *sk, struct sk_buff *skb)
 {
 	if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) {
-		atomic_inc(&sk->sk_drops);
+		sk_drops_inc(sk);
 		sk_skb_reason_drop(sk, skb, SKB_DROP_REASON_XFRM_POLICY);
 		return NET_RX_DROP;
 	}
@@ -1045,7 +1045,7 @@ static void raw_sock_seq_show(struct seq_file *seq, struct sock *sp, int i)
 		0, 0L, 0,
 		from_kuid_munged(seq_user_ns(seq), sk_uid(sp)),
 		0, sock_i_ino(sp),
-		refcount_read(&sp->sk_refcnt), sp, atomic_read(&sp->sk_drops));
+		refcount_read(&sp->sk_refcnt), sp, sk_drops_read(sp));
 }
 
 static int raw_seq_show(struct seq_file *seq, void *v)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index cc3ce0f762ec..732bdad43626 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1787,7 +1787,7 @@ uncharge_drop:
 	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
 
 drop:
-	atomic_inc(&sk->sk_drops);
+	sk_drops_inc(sk);
 	busylock_release(busy);
 	return err;
 }
@@ -1852,7 +1852,7 @@ static struct sk_buff *__first_packet_length(struct sock *sk,
 					IS_UDPLITE(sk));
 			__UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS,
 					IS_UDPLITE(sk));
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			__skb_unlink(skb, rcvq);
 			*total += skb->truesize;
 			kfree_skb_reason(skb, SKB_DROP_REASON_UDP_CSUM);
@@ -2008,7 +2008,7 @@ try_again:
 
 		__UDP_INC_STATS(net, UDP_MIB_CSUMERRORS, is_udplite);
 		__UDP_INC_STATS(net, UDP_MIB_INERRORS, is_udplite);
-		atomic_inc(&sk->sk_drops);
+		sk_drops_inc(sk);
 		kfree_skb_reason(skb, SKB_DROP_REASON_UDP_CSUM);
 		goto try_again;
 	}
@@ -2078,7 +2078,7 @@ try_again:
 
 	if (unlikely(err)) {
 		if (!peeking) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			UDP_INC_STATS(sock_net(sk),
 				      UDP_MIB_INERRORS, is_udplite);
 		}
@@ -2449,7 +2449,7 @@ csum_error:
 	__UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
 drop:
 	__UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
-	atomic_inc(&sk->sk_drops);
+	sk_drops_inc(sk);
 	sk_skb_reason_drop(sk, skb, drop_reason);
 	return -1;
 }
@@ -2534,7 +2534,7 @@ start_lookup:
 		nskb = skb_clone(skb, GFP_ATOMIC);
 
 		if (unlikely(!nskb)) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			__UDP_INC_STATS(net, UDP_MIB_RCVBUFERRORS,
 					IS_UDPLITE(sk));
 			__UDP_INC_STATS(net, UDP_MIB_INERRORS,
@@ -3386,7 +3386,7 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
 		from_kuid_munged(seq_user_ns(f), sk_uid(sp)),
 		0, sock_i_ino(sp),
 		refcount_read(&sp->sk_refcnt), sp,
-		atomic_read(&sp->sk_drops));
+		sk_drops_read(sp));
 }
 
 int udp4_seq_show(struct seq_file *seq, void *v)
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 972bf0426d59..33ebe93d80e3 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -1068,5 +1068,5 @@ void __ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
 		   0,
 		   sock_i_ino(sp),
 		   refcount_read(&sp->sk_refcnt), sp,
-		   atomic_read(&sp->sk_drops));
+		   sk_drops_read(sp));
 }
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 4c3f8245c40f..4026192143ec 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -163,7 +163,7 @@ static bool ipv6_raw_deliver(struct sk_buff *skb, int nexthdr)
 
 		if (atomic_read(&sk->sk_rmem_alloc) >=
 		    READ_ONCE(sk->sk_rcvbuf)) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			continue;
 		}
 
@@ -361,7 +361,7 @@ static inline int rawv6_rcv_skb(struct sock *sk, struct sk_buff *skb)
 
 	if ((raw6_sk(sk)->checksum || rcu_access_pointer(sk->sk_filter)) &&
 	    skb_checksum_complete(skb)) {
-		atomic_inc(&sk->sk_drops);
+		sk_drops_inc(sk);
 		sk_skb_reason_drop(sk, skb, SKB_DROP_REASON_SKB_CSUM);
 		return NET_RX_DROP;
 	}
@@ -389,7 +389,7 @@ int rawv6_rcv(struct sock *sk, struct sk_buff *skb)
 	struct raw6_sock *rp = raw6_sk(sk);
 
 	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) {
-		atomic_inc(&sk->sk_drops);
+		sk_drops_inc(sk);
 		sk_skb_reason_drop(sk, skb, SKB_DROP_REASON_XFRM_POLICY);
 		return NET_RX_DROP;
 	}
@@ -414,7 +414,7 @@ int rawv6_rcv(struct sock *sk, struct sk_buff *skb)
 
 	if (inet_test_bit(HDRINCL, sk)) {
 		if (skb_checksum_complete(skb)) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			sk_skb_reason_drop(sk, skb, SKB_DROP_REASON_SKB_CSUM);
 			return NET_RX_DROP;
 		}
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 6a68f77da44b..a35ee6d693a8 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -524,7 +524,7 @@ try_again:
 	}
 	if (unlikely(err)) {
 		if (!peeking) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			SNMP_INC_STATS(mib, UDP_MIB_INERRORS);
 		}
 		kfree_skb(skb);
@@ -908,7 +908,7 @@ csum_error:
 	__UDP6_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
 drop:
 	__UDP6_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
-	atomic_inc(&sk->sk_drops);
+	sk_drops_inc(sk);
 	sk_skb_reason_drop(sk, skb, drop_reason);
 	return -1;
 }
@@ -1013,7 +1013,7 @@ start_lookup:
 		}
 		nskb = skb_clone(skb, GFP_ATOMIC);
 		if (unlikely(!nskb)) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			__UDP6_INC_STATS(net, UDP_MIB_RCVBUFERRORS,
 					 IS_UDPLITE(sk));
 			__UDP6_INC_STATS(net, UDP_MIB_INERRORS,
diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index cc2b3c44bc05..6c717a7ef292 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -1187,7 +1187,7 @@ static void iucv_process_message(struct sock *sk, struct sk_buff *skb,
 
 	IUCV_SKB_CB(skb)->offset = 0;
 	if (sk_filter(sk, skb)) {
-		atomic_inc(&sk->sk_drops);	/* skb rejected by filter */
+		sk_drops_inc(sk);	/* skb rejected by filter */
 		kfree_skb(skb);
 		return;
 	}
@@ -2011,7 +2011,7 @@ static int afiucv_hs_callback_rx(struct sock *sk, struct sk_buff *skb)
 	skb_reset_network_header(skb);
 	IUCV_SKB_CB(skb)->offset = 0;
 	if (sk_filter(sk, skb)) {
-		atomic_inc(&sk->sk_drops);	/* skb rejected by filter */
+		sk_drops_inc(sk);	/* skb rejected by filter */
 		kfree_skb(skb);
 		return NET_RX_SUCCESS;
 	}
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index e2f7080dd5d7..2b46c0cd752a 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -356,7 +356,7 @@ static void netlink_overrun(struct sock *sk)
 			sk_error_report(sk);
 		}
 	}
-	atomic_inc(&sk->sk_drops);
+	sk_drops_inc(sk);
 }
 
 static void netlink_rcv_wake(struct sock *sk)
@@ -2711,7 +2711,7 @@ static int netlink_native_seq_show(struct seq_file *seq, void *v)
 			   sk_wmem_alloc_get(s),
 			   READ_ONCE(nlk->cb_running),
 			   refcount_read(&s->sk_refcnt),
-			   atomic_read(&s->sk_drops),
+			   sk_drops_read(s),
 			   sock_i_ino(s)
 			);
 
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index a7017d7f0927..9d42c4bd6e39 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2265,7 +2265,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
 
 drop_n_acct:
 	atomic_inc(&po->tp_drops);
-	atomic_inc(&sk->sk_drops);
+	sk_drops_inc(sk);
 	drop_reason = SKB_DROP_REASON_PACKET_SOCK_ERROR;
 
 drop_n_restore:
diff --git a/net/phonet/pep.c b/net/phonet/pep.c
index 62527e1ebb88..4db564d9d522 100644
--- a/net/phonet/pep.c
+++ b/net/phonet/pep.c
@@ -376,7 +376,7 @@ static int pipe_do_rcv(struct sock *sk, struct sk_buff *skb)
 
 	case PNS_PEP_CTRL_REQ:
 		if (skb_queue_len(&pn->ctrlreq_queue) >= PNPIPE_CTRLREQ_MAX) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			break;
 		}
 		__skb_pull(skb, 4);
@@ -397,7 +397,7 @@ static int pipe_do_rcv(struct sock *sk, struct sk_buff *skb)
 		}
 
 		if (pn->rx_credits == 0) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			err = -ENOBUFS;
 			break;
 		}
@@ -567,7 +567,7 @@ static int pipe_handler_do_rcv(struct sock *sk, struct sk_buff *skb)
 		}
 
 		if (pn->rx_credits == 0) {
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			err = NET_RX_DROP;
 			break;
 		}
diff --git a/net/phonet/socket.c b/net/phonet/socket.c
index 2b61a40b568e..db2d552e9b32 100644
--- a/net/phonet/socket.c
+++ b/net/phonet/socket.c
@@ -587,7 +587,7 @@ static int pn_sock_seq_show(struct seq_file *seq, void *v)
 			from_kuid_munged(seq_user_ns(seq), sk_uid(sk)),
 			sock_i_ino(sk),
 			refcount_read(&sk->sk_refcnt), sk,
-			atomic_read(&sk->sk_drops));
+			sk_drops_read(sk));
 	}
 	seq_pad(seq, '\n');
 	return 0;
diff --git a/net/sctp/diag.c b/net/sctp/diag.c
index 23359e522273..996c2018f0e6 100644
--- a/net/sctp/diag.c
+++ b/net/sctp/diag.c
@@ -173,7 +173,7 @@ static int inet_sctp_diag_fill(struct sock *sk, struct sctp_association *asoc,
 		mem[SK_MEMINFO_WMEM_QUEUED] = sk->sk_wmem_queued;
 		mem[SK_MEMINFO_OPTMEM] = atomic_read(&sk->sk_omem_alloc);
 		mem[SK_MEMINFO_BACKLOG] = READ_ONCE(sk->sk_backlog.len);
-		mem[SK_MEMINFO_DROPS] = atomic_read(&sk->sk_drops);
+		mem[SK_MEMINFO_DROPS] = sk_drops_read(sk);
 
 		if (nla_put(skb, INET_DIAG_SKMEMINFO, sizeof(mem), &mem) < 0)
 			goto errout;
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index e028bf658499..1574a83384f8 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2366,7 +2366,7 @@ static void tipc_sk_filter_rcv(struct sock *sk, struct sk_buff *skb,
 		else if (sk_rmem_alloc_get(sk) + skb->truesize >= limit) {
 			trace_tipc_sk_dump(sk, skb, TIPC_DUMP_ALL,
 					   "err_overload2!");
-			atomic_inc(&sk->sk_drops);
+			sk_drops_inc(sk);
 			err = TIPC_ERR_OVERLOAD;
 		}
 
@@ -2458,7 +2458,7 @@ static void tipc_sk_enqueue(struct sk_buff_head *inputq, struct sock *sk,
 		trace_tipc_sk_dump(sk, skb, TIPC_DUMP_ALL, "err_overload!");
 		/* Overload => reject message back to sender */
 		onode = tipc_own_addr(sock_net(sk));
-		atomic_inc(&sk->sk_drops);
+		sk_drops_inc(sk);
 		if (tipc_msg_reverse(onode, &skb, TIPC_ERR_OVERLOAD)) {
 			trace_tipc_sk_rej_msg(sk, skb, TIPC_DUMP_ALL,
 					      "@sk_enqueue!");
@@ -3657,7 +3657,7 @@ int tipc_sk_fill_sock_diag(struct sk_buff *skb, struct netlink_callback *cb,
 	    nla_put_u32(skb, TIPC_NLA_SOCK_STAT_SENDQ,
 			skb_queue_len(&sk->sk_write_queue)) ||
 	    nla_put_u32(skb, TIPC_NLA_SOCK_STAT_DROP,
-			atomic_read(&sk->sk_drops)))
+			sk_drops_read(sk)))
 		goto stat_msg_cancel;
 
 	if (tsk->cong_link_cnt &&