From nobody Wed Sep 10 23:46:16 2025 Received: from mail-pg1-f179.google.com (mail-pg1-f179.google.com [209.85.215.179]) (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 3FBCC334728 for ; Wed, 10 Sep 2025 16:24:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757521472; cv=none; b=KwTFQxcHEinS+exWeHGaDEuP/7K11/WgU0KmMZN3tzXlXeKA5pdwf+Z4TO6/s4LERVHNyXKQ5n4M3dJ3SsAQu8E9P3+LBuqo1y6J5KJzB6/qEDg1RjsAQpkYwLeTrpbz4DpNa4IMoqdkSrUCCFsTsWIZsNethScCmE+A6HH/oqY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757521472; c=relaxed/simple; bh=XKhu0ButZfP1eFEp10IuKdFzc3bsJodNLb7lW4zaCgw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=sFz+kVLzg6o4AVKviAE8RTqHVZGseIy/osuMm98ta5CY4myuzDtP4y541BStZyjABnPPMbf+0+X5+u9a4AefWjcoMAZ6CtS0OxqNEDr1gz12KG7xdQjyZwe9ZeWGYmRADzmFOvOCR0AUkeCgYQWscvXrRaygr0yk9g9/WakHfD4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fomichev.me; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.215.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fomichev.me Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pg1-f179.google.com with SMTP id 41be03b00d2f7-b47173749dbso4903565a12.1 for ; Wed, 10 Sep 2025 09:24:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757521470; x=1758126270; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=p83w/Q/IRim7hnms2A7dQTsuzOFdw9GVdjRXWe+p5Ww=; b=QAnZG1YFEeSO+k0dogXMazUDcu1HAjnsBtipGZxOWuOiwBKBBBpxne/Be2YlNF3IcX EqXJzUzpK9/p/m/ppfAfy3FFdT4fMxcDbvK9I8n15SCDzRoxNTMyVZ34QP+LSPDWF1JQ LjFt6ltQGBdS4i0WdGxzQYtNcRcx8W5yHNUqed8a3WoLJrUEdWSJJKpFSq+Q3yDhFbZ9 YOy7S1qEg6DhNHJcYKl4XV5Dze41mUOX70lLFCsgKgF7psjL4xjk8ueJVd9dj3PUpwrT nrg34MBYiFNSVPQvXGilo1EvrZyYUiSv4TbBKJ/6fhNciGaC3yQE0YkV5LxhrPqb9pTw fAiw== X-Forwarded-Encrypted: i=1; AJvYcCURROoRKVro0b0FCZQx5RoeSp5503ekLBpdTexqGJ5dL8qHL3rK2Z+Y6gc3zciq1peclTlxOSQiQwSvoxA=@vger.kernel.org X-Gm-Message-State: AOJu0YxhdVgv3s/je+GIqw4MH582Gp48zSYUBQPOek4SLMmXMoRJLNR/ Wo4YeZBZSKJoYfZ4bKfr900xxL13qhiQMol42NboWs1fh48q8AcAeGg= X-Gm-Gg: ASbGncsL7nhK8DGwn+8fZ764Hv5HBffkxegi6z2yp7eHYoInMwlFFUrVPblbUyWrSaH EoJwY9fN7p7Rhxn5doMHq29YGMgLdLYXIOoBB0R04rIiucfem0/aTypYiYCQ2j6huNHv29WEKxI tnuNUZrX966smj1CoUJCBv//fTsjUvMqjFokmk+AuYGN7HtLa1uPE68ntvTAP4W01B8BGxrlbI2 lDhYJn5dv5D8Uil80w5fFaCw7Rf1eRamd8xeb56JK6y8UfUlZ2B9bdnV7mmr2aVS7yUDXMOf09b HBtCVz4Z73uchEQ44hS0EtJzwpo151oaMaEaLjnn/SOIA5KXBZcs8nrud5aBSgehcH6M7E+0P3F mkA7lUIBm9lsJffeNhaPStuB2jeTxtoxz7X+C2EK5KFmxdusW4fwdQkWJHuIpp77/1MFDwlJI8c dF8bxigqKaeulRGH+a1e87n0Ay7Cluv5l+jIBZ0Mcp4SZH1RdIUFUr5IIQP1MfcNj79zZ+xvoPX I5P2E3pRLsQNBA= X-Google-Smtp-Source: AGHT+IFiww+cMWoD4/EmybvtoEqMGorFwlUf88+GYf5wrs1Lt1yUTpI2n83Aakd3i8q2nSdM+bs55g== X-Received: by 2002:a17:902:ef48:b0:259:5284:f87b with SMTP id d9443c01a7336-2595284fe1fmr78470345ad.16.1757521470367; Wed, 10 Sep 2025 09:24:30 -0700 (PDT) Received: from localhost (c-73-158-218-242.hsd1.ca.comcast.net. [73.158.218.242]) by smtp.gmail.com with UTF8SMTPSA id d9443c01a7336-25a27425dc1sm31958965ad.20.2025.09.10.09.24.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Sep 2025 09:24:30 -0700 (PDT) From: Stanislav Fomichev To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, ncardwell@google.com, kuniyu@google.com, dsahern@kernel.org, horms@kernel.org, linux-kernel@vger.kernel.org, Mina Almasry Subject: [PATCH net-next v2] net: devmem: expose tcp_recvmsg_locked errors Date: Wed, 10 Sep 2025 09:24:29 -0700 Message-ID: <20250910162429.4127997-1-sdf@fomichev.me> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" tcp_recvmsg_dmabuf can export the following errors: - EFAULT when linear copy fails - ETOOSMALL when cmsg put fails - ENODEV if one of the frags is readable - ENOMEM on xarray failures But they are all ignored and replaced by EFAULT in the caller (tcp_recvmsg_locked). Expose real error to the userspace to add more transparency on what specifically fails. In non-devmem case (skb_copy_datagram_msg) doing `if (!copied) copied=3D-EFAULT` is ok because skb_copy_datagram_msg can return only EFAUL= T. Reviewed-by: David Ahern Reviewed-by: Mina Almasry Reviewed-by: Eric Dumazet Signed-off-by: Stanislav Fomichev -- v2: s/err <=3D 0/err < 0/ since we never return 0 (Jakub) --- net/ipv4/tcp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 588932c3cf1d..9c576dc9a1f7 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2818,9 +2818,9 @@ static int tcp_recvmsg_locked(struct sock *sk, struct= msghdr *msg, size_t len, =20 err =3D tcp_recvmsg_dmabuf(sk, skb, offset, msg, used); - if (err <=3D 0) { + if (err < 0) { if (!copied) - copied =3D -EFAULT; + copied =3D err; =20 break; } --=20 2.51.0