From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Axtens Subject: Re: [PATCH v3 1/2] net: create skb_gso_validate_mac_len() Date: Tue, 30 Jan 2018 13:42:38 +1100 Message-ID: <87d11srrs1.fsf@linkitivity.dja.id.au> References: <20180130011447.24916-1-dja@axtens.net> <20180130011447.24916-2-dja@axtens.net> <1517276779.3715.92.camel@gmail.com> <1517277541.3715.95.camel@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Manish.Chopra@cavium.com, Jason Wang , "Pravin Shelar" , Marcelo Ricardo Leitner To: Eric Dumazet , netdev@vger.kernel.org Return-path: Received: from mail-pg0-f47.google.com ([74.125.83.47]:36769 "EHLO mail-pg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752076AbeA3Cmt (ORCPT ); Mon, 29 Jan 2018 21:42:49 -0500 Received: by mail-pg0-f47.google.com with SMTP id k68so6053217pga.3 for ; Mon, 29 Jan 2018 18:42:49 -0800 (PST) In-Reply-To: <1517277541.3715.95.camel@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Hi Eric, >> skb_gso_transport_seglen(skb) is quite expensive (out of line) >> >> It is unfortunate bnx2x seems to support 9600 MTU ( >> ETH_MAX_JUMBO_PACKET_SIZE ), because 100 bytes of headers can be too >> small in some cases. >> >> Presumably we could avoid calling the function for standard MTU <= >> 9000 Yes, it is an expensive call. I will send another version where we only call the expensive path in the jumbo frame case. I'll wait until tomorrow in case there is any more feedback in the next 24 hours or so. > Also are we sure about these bnx2x crashes being limited to TSO ? > > Maybe it will crash the same after GSO has segmented the packet and we > provide a big (like 10,000 bytes) packet ? I do not believe upper stack > will prevent this. We did test with TSO off and that was sufficient to prevent the crash. You are right that the upper stack sends down the 10k packet, so I don't know why it prevents the crash. But we did definitely test it! I don't have access to the firmware details but I imagine it's an issue with the offloaded segmentation. Thanks for your patience with the many versions of this patch set. Regards, Daniel