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 A5F0337AA79; Thu, 8 Oct 2026 01:57:29 +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=1791424650; cv=none; b=UE3lNM9wtAasSYHRuupE8tO1pC6chI6QjHQVVF2NCR5/dLOrWTF4FaZQ6zFFdGWLKRjU8qpnXMVNSiBzDQQy3n+0vZOLI5vArIEK6a0oV4jmor/1C6Uy2zsL8OMVXC0pu25E2GcxVfQfIsXrm6HzzdmP7+5o85Rv9zN4gHXvFGY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791424650; c=relaxed/simple; bh=bwDRfHmL+0pbMnJR1GsK7JFfccS9jDbWsMhcIV6pmxs=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=IzWLK7BxJptBrE7eQ4ERl0LHQw3R0GXwVUmaz/FQ0DjezckqttDZJmOL2MBH5fSo0Kmnz4aQsQkyoX6kVk4YwB8v+/zBmIfaMrbTUJ0W+i8kUJ/Bx2XMVkwAufEdxpg7+Vjz7s67Zr0zdEDj4Aa1K8m0PVNBqqOoASWC0Gq4758= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NWFzYyQq; 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="NWFzYyQq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 783F11F000FF; Thu, 8 Oct 2026 01:57:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791424649; bh=cyaBNpcWG/sN/H/GV35qpL+l/NWPhdj0dPzl1NaiBHg=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=NWFzYyQq8o/+WvrLyKjRlVhFoRbgI+Tjgo2xAmC4AOFqO1Ij/QPHRJlShg0cPpeyZ B5bhOd4JOHQfv7j36CdlRIG1JZqABSJiety8It+M6BgRdZmbQv6J6tjjLfcO2xtrtX 9d7te4Xw8qOfZJ43JC7eC0I7oDI/h3KKkYcFQDC3QLlGUqr5bTWp/I6KGOiXWZGoyh eiGZ1BtDKqB+CfBOQss+JTsaPIRFsF8/uOpaDiAdKjgszWUZ+bT4PdkysAcMpUeCpe uXzsDH/Rp23D3H65GoWfLveDSb+9kvpJQX0fFwlqLQjqFB78FSM3Xy5mXNdz5nUyfK 8mqyyhzIebSUQ== Date: Wed, 7 Oct 2026 18:57:27 -0700 From: Jakub Kicinski To: Tony Nguyen Cc: davem@davemloft.net, pabeni@redhat.com, edumazet@kernel.org, andrew+netdev@lunn.ch, netdev@vger.kernel.org, Ding Meng , florian.bezdeka@siemens.com, p@1g4.org, tkusters@aweta.nl, jiayuan.chen@linux.dev, pulehui@huawei.com, vinicius.gomes@intel.com, maciej.fijalkowski@intel.com, magnus.karlsson@intel.com, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, bpf@vger.kernel.org, richardcochran@gmail.com, dima.ruinskiy@intel.com, stable@vger.kernel.org, Aleksandr Loktionov , Piotr Kwapulinski Subject: Re: [PATCH net 1/6] igc: Fix RX HW timestamp reporting when NET_RX_BUSY_POLL is disabled Message-ID: <20261007185727.68180ce3@kernel.org> In-Reply-To: <20261001222443.3500206-2-anthony.l.nguyen@intel.com> References: <20261001222443.3500206-1-anthony.l.nguyen@intel.com> <20261001222443.3500206-2-anthony.l.nguyen@intel.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 1 Oct 2026 15:24:34 -0700 Tony Nguyen wrote: > When CONFIG_NET_RX_BUSY_POLL is deactivated, fetching RX HW timestamps > from the NIC no longer works as expected, often resulting in incorrect > or negative values such as "HW raw -121948.050407424". > > This occurs because disabling CONFIG_NET_RX_BUSY_POLL disables the > SKB NAPI mapping in __skb_mark_napi_id(). Consequently, get_timestamp() > fails to perform its driver lookup, and the igc driver's struct > net_device_ops::ndo_get_tstamp is never invoked. > > Instead, get_timestamp() falls back to use shhwtstamps(skb)->hwtstamp, > a field that the driver has not populated. This results in incorrect > timestamps. > > Fix this by populating the hwtstamp field with the correct timestamp > in the default timer when CONFIG_NET_RX_BUSY_POLL is disabled. > The "igc_adapter" is passed to igc_construct_skb() to enable > igc_ptp_rx_pktstamp() to access the necessary adapter details for > adjusting the timestamp. looks like a driver workaround for a generic problem a better fix is likely needed here