From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f201.google.com (mail-qt1-f201.google.com [209.85.160.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5199639527A for ; Thu, 9 Apr 2026 10:11:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775729511; cv=none; b=GarbAcqrUHvrLfPC8nudaZ9KABTUx7mxaqBnZL1EG5J2kiTyxuHEtjCEDdvBbtMucvIMRDF4C1efZWZVCGrJte4zPVFfvXwjUyhkn7HpTkgdgLy7GZRqJz7BS7cJ2HVbQHL80PhA3nm/0d1RG1hsito2W/cgBHrHnUfIl3CGrKI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775729511; c=relaxed/simple; bh=nIPqjGkG6TQu79i6M/x5vlhg6SHXJOSsigN0FTYlxa0=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=cGprIfjIEsea/LLkNhyRaZ233+Cw9H6fmfcYwz9FWE9OROn2x1NCUajDlRxg7LmUwU7//Xd/1n57DJNyZ+VccvdAxRofxFZzyU6YrBYwv0WBx74WDfWFrP+fkxH2m+u9tJ/uvRB8M0/Dkg0AOQ9nocMkayGB0UklBcTAUgQKnkI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=WN9v1pK1; arc=none smtp.client-ip=209.85.160.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="WN9v1pK1" Received: by mail-qt1-f201.google.com with SMTP id d75a77b69052e-50d68dbb77bso16073751cf.2 for ; Thu, 09 Apr 2026 03:11:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1775729509; x=1776334309; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=W4smQAEcqLSJsw172+o+NwZaU/uAra093pBg7Pxg5K4=; b=WN9v1pK10JUA7wB1fy74V/RPrQWIj+dxoMvP8X1yrdZF48c3BRgKzQrhsStVgDROYg 6EjdpUyxQKi1s5nQCof30lJyou1EesZEfEJ1CbuYofByUgceSZlj6WieC0dmfe9PDlrv YDAgRgP/i175heixUE63uiDG1jk+8MuYy0OcG/SMfMNXkBbFYE/WDQsdZ6DReTu2EXwt Sb0llCMV9sX8eWn1DTwQiKuVj7kcs8463WY8pv5d0bdnhYYZnMIxLMyQbebhbqpyJLAJ 3DBnoGpeFA7aluUNTrtlQjXqU9eRdYqwwPqjIBXImLmJRlWUG+Vba6X03lxJgGA63hHc W0rA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775729509; x=1776334309; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=W4smQAEcqLSJsw172+o+NwZaU/uAra093pBg7Pxg5K4=; b=mTYwrjf4p4IJ05/qtpOyjsWYWuKzIUfC3Us6xz09H4OLIM4Wb32DIsD3oaLcPZ46l0 evAd5Fq9Nf5iIgLAbBxEZ09a0XaFbHnjnToBpq/iwSdb6bGTdKcT0QDoV+y39GPCCM8z tnNVGg1m4nV591NIHW/Zg/7V+wX6z7y20c0VPb7pbnmBq6n0GhBtE2zrzWR7bn90y6sl v5T20Risb5ijT1WiJOpTN5OJlxrOGNpARMkMQlXoRspsCrcssMpDtlRS8ASodMvtYEwG 6aELNENky8VsQq5vhdSL6UcoLBocNnZyyioFqmLzQtCaen6CutMDgeLwgz6fXHiUMlUJ T5xw== X-Forwarded-Encrypted: i=1; AJvYcCXl8mBFP51nzgFQ5T3+IH7MTqQE/YB9tkUkcV/8vfy28KhbFQ5YcOk3MREpuL2ASrA7MF1TYMI=@vger.kernel.org X-Gm-Message-State: AOJu0YziGqau+ZKD+Ol5T832Y3PIOvSVRo5NT44cBIauFA4bNu8w8V1W plG/+JDpnDxm4jJK7VrjaNfq2CrJK3o+lBKrQOpp3sQ7Ic6lUgRVJqlLGdP2rc9+4ulTXaPKkp2 JzoGEr/T56DVg1g== X-Received: from qti6.prod.google.com ([2002:a05:622a:8346:b0:509:17b9:4bbb]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:ac8:6906:0:b0:50b:3d9f:384e with SMTP id d75a77b69052e-50d62cbf981mr353487361cf.44.1775729509089; Thu, 09 Apr 2026 03:11:49 -0700 (PDT) Date: Thu, 9 Apr 2026 10:11:47 +0000 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.53.0.1213.gd9a14994de-goog Message-ID: <20260409101147.1642967-1-edumazet@google.com> Subject: [PATCH net-next] tcp: return a drop_reason from tcp_add_backlog() From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Neal Cardwell , Kuniyuki Iwashima , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet Content-Type: text/plain; charset="UTF-8" Part of a stack canary removal from tcp_v{4,6}_rcv(). Return a drop_reason instead of a boolean, so that we no longer have to pass the address of a local variable. $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-37 (-37) Function old new delta tcp_v6_rcv 3133 3129 -4 tcp_v4_rcv 3206 3202 -4 tcp_add_backlog 1281 1252 -29 Total: Before=25567186, After=25567149, chg -0.00% Signed-off-by: Eric Dumazet --- include/net/tcp.h | 3 +-- net/ipv4/tcp_ipv4.c | 21 +++++++++------------ net/ipv6/tcp_ipv6.c | 3 ++- 3 files changed, 12 insertions(+), 15 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 6156d1d068e142f696ec9dfff63e3aaebb0171bc..fce4b653c23ec790f561d577fcd6160d3d92e3c0 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1680,8 +1680,7 @@ static inline bool tcp_checksum_complete(struct sk_buff *skb) __skb_checksum_complete(skb); } -bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, - enum skb_drop_reason *reason); +enum skb_drop_reason tcp_add_backlog(struct sock *sk, struct sk_buff *skb); static inline int tcp_filter(struct sock *sk, struct sk_buff *skb, enum skb_drop_reason *reason) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 69ab236072e7142d5ca9d0703d99f02c1e17c738..c9bbbf32364827d341b4c1fd77617031b0739c50 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1900,8 +1900,7 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) } EXPORT_SYMBOL(tcp_v4_do_rcv); -bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, - enum skb_drop_reason *reason) +enum skb_drop_reason tcp_add_backlog(struct sock *sk, struct sk_buff *skb) { u32 tail_gso_size, tail_gso_segs; struct skb_shared_info *shinfo; @@ -1929,10 +1928,9 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, if (unlikely(tcp_checksum_complete(skb))) { bh_unlock_sock(sk); trace_tcp_bad_csum(skb); - *reason = SKB_DROP_REASON_TCP_CSUM; __TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS); __TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS); - return true; + return SKB_DROP_REASON_TCP_CSUM; } /* Attempt coalescing to last skb in backlog, even if we are @@ -2006,7 +2004,7 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPBACKLOGCOALESCE); kfree_skb_partial(skb, fragstolen); - return false; + return SKB_NOT_DROPPED_YET; } __skb_push(skb, hdrlen); @@ -2031,15 +2029,13 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, if (unlikely(err)) { bh_unlock_sock(sk); if (err == -ENOMEM) { - *reason = SKB_DROP_REASON_PFMEMALLOC; __NET_INC_STATS(sock_net(sk), LINUX_MIB_PFMEMALLOCDROP); - } else { - *reason = SKB_DROP_REASON_SOCKET_BACKLOG; - __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPBACKLOGDROP); + return SKB_DROP_REASON_PFMEMALLOC; } - return true; + __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPBACKLOGDROP); + return SKB_DROP_REASON_SOCKET_BACKLOG; } - return false; + return SKB_NOT_DROPPED_YET; } static void tcp_v4_restore_cb(struct sk_buff *skb) @@ -2247,7 +2243,8 @@ int tcp_v4_rcv(struct sk_buff *skb) if (!sock_owned_by_user(sk)) { ret = tcp_v4_do_rcv(sk, skb); } else { - if (tcp_add_backlog(sk, skb, &drop_reason)) + drop_reason = tcp_add_backlog(sk, skb); + if (drop_reason) goto discard_and_relse; } bh_unlock_sock(sk); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 8dc3874e8b9252da60f21ad77a5ca834532e650a..1d37826e8480f203846e963418cfe2085131adfa 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1877,7 +1877,8 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) if (!sock_owned_by_user(sk)) { ret = tcp_v6_do_rcv(sk, skb); } else { - if (tcp_add_backlog(sk, skb, &drop_reason)) + drop_reason = tcp_add_backlog(sk, skb); + if (drop_reason) goto discard_and_relse; } bh_unlock_sock(sk); -- 2.53.0.1213.gd9a14994de-goog