From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E99C537F313 for ; Wed, 9 Sep 2026 17:32:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788975139; cv=none; b=TQ/yQ0rypLy/Dnknsf3T1OUGJAQG7RJ7w/behluKTtGnQ03hiPRChSO96JrnGp6cPb6dRF1xLHms8QczUouEZMH1enAdTN01Ztmo9DKEJJPu/wcXNGLSV0XSPhyQzGrUG8xtnxp54mJXwJW7AspJiJ3DSNE3lawXzI75KpL5r1M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788975139; c=relaxed/simple; bh=Ae0ZlgKsO7EE3vcYjsTbwQrOKIj1UMbsO0kW7O8Xu5w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gM6GtWz3ZVo2AKfAbSVJYPODH0v6fbfV6YkTCgz5bmEhpHONIaBCiOhA4l40yyoFnsq/MA1oelNAssCvbIODhIAVk6mDHChT9FyInf5BtyC5f3bELYi52FgaNKfudZDCWfoJ92mvF5/UK8I3x3CPvT8D5dA4s/hhbUWvo/VeF8M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Scm77xFp; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Scm77xFp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EBBB81F00898; Wed, 9 Sep 2026 17:32:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788975137; bh=zfmRfOUZvurm8uCCx60ft2MdU9luG8Le4ffEmdhJieM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Scm77xFpq+xPW5+DpItPdZBYetP6h0kDGgjtN+trDjUDUSvvDDaXdCNSrV0HiD5Xi V24nj1PlPvhXO+yCWXemezrEwNCesalUE59EcTcPtgEsfEpWOOKMvA3tei4Q5+B3YN l6qQCGiiBSE2cHAb7wVaLj580mjhkxwtS2GGuL+He0XSwhIku5Ywo5tQKg7jWw6MLp F3H4tjNFqwtv8TENqHdaXyT2HwLcDX6bJ+HLKiKN/FnpNGxxOAoPFfVKqH7vUGLFn0 XVK48iKB/4KSPuqoJWDPinN5fPYUV1HsAv+XEgHeTUug7+tcgLU78CdLKA8Jbx80XB 6fgFBIXAeH4PQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Glenn Judd , Tariq Toukan , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18.y 2/2] net/mlx5e: do not HW-GRO coalesce small frames Date: Wed, 9 Sep 2026 13:32:14 -0400 Message-ID: <20260909173214.3296617-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260909173214.3296617-1-sashal@kernel.org> References: <2026090308-macarena-speckled-769c@gregkh> <20260909173214.3296617-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Glenn Judd [ Upstream commit e2466392a0b8496000e12181cb1ee1535eb0da25 ] When hardware GRO (SHAMPO) coalesces a small IPv4/TCP segment that was padded up to the 60-byte minimum Ethernet frame, the trailing padding is folded into the merged payload causing padding to be delivered to the user as payload. Detecting and reproducing the issue: the selftest tools/testing/selftests/drivers/net/gro.py subtest hw_ipv4_data_lrg_1byte sends {100, 1} expecting to receive {101}. In current code, it receives {106} (100 + 1 payload + 5 pad) instead. This patch avoids giving the user padding as payload by simply not coalescing small packets (which fails the subtest; the same approach and behavior as sw gro). This gains code simplicity at the cost of more computation (passing an extra skb up the stack) for small packets that could be coalesced. The threshold is chosen as ETH_ZLEN + 2 * VLAN_HLEN. This is the largest frame that may still contain minimum-frame padding (+ 2 VLAN tags), so anything larger is safe to consider for coalesce. (We do not include ETH_FCS_LEN in that threshold computation as netdev_fix_features() drops NETIF_F_GRO_HW whenever NETIF_F_RXFCS is set, so retained FCS can't reach this path.) Fixes: 92552d3abd32 ("net/mlx5e: HW_GRO cqe handler implementation") Cc: stable@vger.kernel.org Signed-off-by: Glenn Judd Signed-off-by: Tariq Toukan Link: https://patch.msgid.link/20260816064259.3279548-1-tariqt@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c index 8a61c958c5679..17b74a97138b5 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -2401,6 +2401,11 @@ static void mlx5e_handle_rx_cqe_mpwrq_shampo(struct mlx5e_rq *rq, struct mlx5_cq data_offset = wqe_offset & (page_size - 1); page_idx = wqe_offset >> rq->mpwqe.page_shift; + if (unlikely(cqe_bcnt <= ETH_ZLEN + 2 * VLAN_HLEN)) { + match = false; + flush = true; + } + if (*skb && !(match && mlx5e_hw_gro_skb_has_enough_space(*skb, data_bcnt, page_size))) { -- 2.53.0