From: Eric Dumazet <edumazet@google.com>
Date: Thu, 9 Apr 2026 14:56:23 +0000 (+0000)
Subject: tcp: change tcp_filter() to return the reason by value
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=97449a5f1a586d2befde5297b0fcb0bfdade774e;p=thirdparty%2Fkernel%2Flinux.git

tcp: change tcp_filter() to return the reason by value

sk_filter_trim_cap() will soon return the reason by value,
do the same for tcp_filter().

Note:

tcp_filter() is no longer inlined. Following patch will inline it again.

$ scripts/bloat-o-meter -t vmlinux.4 vmlinux.5
add/remove: 2/0 grow/shrink: 0/2 up/down: 186/-43 (143)
Function                                     old     new   delta
tcp_filter                                     -     154    +154
__pfx_tcp_filter                               -      32     +32
tcp_v4_rcv                                  3152    3143      -9
tcp_v6_rcv                                  3169    3135     -34
Total: Before=29722640, After=29722783, chg +0.00%

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260409145625.2306224-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 6156d1d068e1..098e52269a04 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1683,12 +1683,14 @@ static inline bool tcp_checksum_complete(struct sk_buff *skb)
 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb,
 		     enum skb_drop_reason *reason);
 
-static inline int tcp_filter(struct sock *sk, struct sk_buff *skb,
-			     enum skb_drop_reason *reason)
+static inline enum skb_drop_reason
+tcp_filter(struct sock *sk, struct sk_buff *skb)
 {
 	const struct tcphdr *th = (const struct tcphdr *)skb->data;
+	enum skb_drop_reason reason;
 
-	return sk_filter_trim_cap(sk, skb, __tcp_hdrlen(th), reason);
+	sk_filter_trim_cap(sk, skb, __tcp_hdrlen(th), &reason);
+	return reason;
 }
 
 void tcp_set_state(struct sock *sk, int state);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 69ab236072e7..e2da3246a641 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2164,7 +2164,8 @@ lookup:
 		}
 		refcounted = true;
 		nsk = NULL;
-		if (!tcp_filter(sk, skb, &drop_reason)) {
+		drop_reason = tcp_filter(sk, skb);
+		if (!drop_reason) {
 			th = (const struct tcphdr *)skb->data;
 			iph = ip_hdr(skb);
 			tcp_v4_fill_cb(skb, iph, th);
@@ -2225,7 +2226,8 @@ process:
 
 	nf_reset_ct(skb);
 
-	if (tcp_filter(sk, skb, &drop_reason))
+	drop_reason = tcp_filter(sk, skb);
+	if (drop_reason)
 		goto discard_and_relse;
 
 	th = (const struct tcphdr *)skb->data;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 8dc3874e8b92..d64d28e9842f 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1794,7 +1794,8 @@ lookup:
 		}
 		refcounted = true;
 		nsk = NULL;
-		if (!tcp_filter(sk, skb, &drop_reason)) {
+		drop_reason = tcp_filter(sk, skb);
+		if (!drop_reason) {
 			th = (const struct tcphdr *)skb->data;
 			hdr = ipv6_hdr(skb);
 			tcp_v6_fill_cb(skb, hdr, th);
@@ -1855,7 +1856,8 @@ process:
 
 	nf_reset_ct(skb);
 
-	if (tcp_filter(sk, skb, &drop_reason))
+	drop_reason = tcp_filter(sk, skb);
+	if (drop_reason)
 		goto discard_and_relse;
 
 	th = (const struct tcphdr *)skb->data;